I think the compression/cam lift correlation is not as important as the compression/cam duration one. Basically the longer duration cams (and usually a corresponding overlap increase) moves the power up the scale and you might get some lower end power loss. Increasing compression has the effect of putting some or all of that lower end power back in. Higher lift cams will give a boost to the low-mid power but often require a bit more duration if the profile isn't going to be too tough on the valve train. Someone who actually understands this properly like "djl" would probably be able to explain it better.

 

You'll do better if the compression is at least 10:1 for the 251's. That is what my bike has, and it works out quite well.

 

I'm at almost the same numbers as you are with 204's. Almost the same combo as you, 103" and the heads have a street port done on them set the deck at .004 and a 0.30 headgasket

 

I like mine. If your running any hiils loaded up not the best. It will scream with just you on it. Two up runs good but have to shift down when getting on it.