Marco, I appreciate the effort you put into that write-up, I should have made it clear that my tune was done Advanced. Will confirm which table is front before adjusting: Thanks for the tip.

My a/f data logging setup is nearly complete. I wasn't able to finish this weekend but got close to it. Will be doing what you suggested and a bit more:
1. check a/f to see if rear is lean. If it is, look for cause in map and attempt to adjust. If no apparent cause found...
1a. swap injectors front to rear and see if problem follows the rear injector
2. tweak timing to determine impact on temps. If this and the above doesn't bring rear temp down enough, then...
3. inspect rear cylinder oil jet









S & S allows dyno break-ins, but in a controlled manner that essentially replicates a street "soft" break-in. Straight from their website:

Engine Break-In Procedure
Note: S&S engines are designed for high performance and as such are not as tolerant of inadequate break-in as stock or lower performance engines. Correct breakin will assure longer engine life and will prevent unnecessary engine damage. Engine damage caused by improper break-in is not covered under the S&S warranty.

A. Initial start up. Run engine approximately one minute at 1250-1750 rpm. DO NOT crack throttle or subject to any loads during this period as head gaskets are susceptible to failure at this time. During this time, check to see that oil pressure is normal, that oil is returning the oil tank, and that no leaks exist.

B. Shut off engine and thoroughly check for any leaks or other problems. Let engine cool to the touch.

C. After engine has cooled, start up again and allow the motor to build some heat. Engine should be run no longer than three to four minutes. When the cylinders become warm/ hot to the touch (approximately 150°) shut the motor down and let it cool to room temp. Follow the same cautions as for the initial start-up, and continue to watch for problems.

D. Repeat this procedure 3 or 4 times. Each successive time it should take slightly longer to warm up and you can increase the temp slightly each time (+10°). You can be more liberal each time with the rpm, gently vary rpm continuously from idle up to 2500 rpm in the final cycle. Don't be too concerned with final carb settings at this time because idle speed and mixture cannot be correctly set until the motor reaches full operating temperature. The motor should not reach that temperature during these cycles. Do not allow engine temperature to become excessive. After the motor has cooled to room temperature for the final time you are ready to start the 1000 mile engine break-in process.

E. The first 50 miles are most critical for new rings and piston break-in. Engine damage is most likely to occur during this period. Keep heat down by not exceeding 2500 rpm. Avoid lugging the motor, riding in hot weather or in traffic. Vary the engine speed. Do not lug the engine. We recommend changing the oil at 50 miles.

F. The next 500 miles should be spent running engine no faster than 3500 rpm or 60 mph. Avoid continuous steady speeds, and do not lug the engine. Vary engine rpm. We recommend changing the oil again at 500 miles.

CAUTION: Lugging or running engine prematurely at sustained high rpm may result in damage to pistons and other engine components. S&S voids it's guarantee if engine is not broken in properly.

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And the S & S take on dyno tuning, again from their website:

Dyno Break-In Procedure

1. Follow the same procedure outlined above for initial start-up and heat cycling the engine.
2. Run the bike for 25 miles on the dyno under varying speeds and loads while going up and down through the gears. Keep engine RPM below
   3,500 RPM but do not lug the engine. The dyno must be operated so the engine runs under a load roughly equal to the power needed to move
   the bike down the road, this would be about 12 hp at 55 mph. Keep engine head temperatures below 200 °F at the temp sensor or surface of
   the head. Stop and cool the engine if needed.
3. Allow the engine to cool down to room temperature
4. Run the bike for 25 more miles (50 miles total) under varying speeds, loads, gears as before. Make sure there is some load on the engine.
   Keep engine speed below 4,250 rpm but do not lug the engine. Limited short bursts of throttle can aid in ring seating. Keep engine head
   temperatures below 225 °F at the temp sensor or surface of the head.
5. After the first 50 miles on the dyno, it is recommended the normal break-in schedule be followed under normal riding conditions on the street.
   See Step 5 above.

I can do the basic break-in tune on the street by bringing my laptop with me and stopping to analyze and adjust on-the-go. It doesn't need to be perfect for the initial break-in period, just good enough to get me through it. And again, I'm not saying the issue isn't timing: I am only saying I don't need to pay someone $400 of dyno time to get me through that 1st thousand miles.

Thanks max, I'll bump the timing in 6-degree increments rather than 3.

Lo, I totally understand what you're saying and agree that it's a great tool. It's also a very expensive one. I don't need it dialed-in for the 1st 1K miles, I just need it running well enough. I'll get that final dial-in at the end of that break-in. With the a/f data logging rig I've installed, and the help of you bright people, I'm totally confident I can get this mixture and spark under control till I get back on the dyno.