"Squish"???I'd start with a good maintenance check, a good low/mid pipe, and then a head mod.. Much more could be done but I would start there.. Like anything else it will depend on the budget but those few things will be the best bang for the buck imo..
Read on how to set your squish clearance, its free and you will gain a few ponies just by getting things set how they should be in the first place..
Wow dude thanks!!http://www.klemmvintage.com/squish&comp.htm
I'll post up some more links. After reading a bit you should get the jist. You can shave the head with a flat hand file to adjust the ''squish" but it takes some elbow grease and a few basic tools..