I have a 2006 FLSTC and I did the S&S 97 inch big bore kit with SE ported heads and still have S&S 510 gear drive cams in it. I’m planning on changing cams at some point wit 583 EZ start cams. When it was tuned after break in, it was putting out 102 ft/lbs torque and 98 hp with the 510’s. Problem was that the cams didn’t kick in at a low enough rpm.
The problem is you didn't use the right pistons or set your heads up right to have the right compression for the cams if your bottom is soft. If you did(which I believe is the case based on your numbers), you'll be in big trouble going to a grunt cam with an IVC of 18° from a cam with an IVC of 38° which is a good cam with the right compression. What you need is a cam with more lift, not one with an IVC of 20° less. Like the Woods TW5-6.