The 110" heads are not bad. You need to 'flycut' around .050 off the combustion chamber ,that gives you more comp. {with flat top pistons} but the big reasons is it makes the combustion chamber smaller {compact} for a better burn, and modify the stock valves {backcut,radius,etc} and the key is the seats ,or should I say ,how many angles ,and the width of each angle. Very little shaping in the ports because they are {in my opion} big. I ALWAYS shorten the guides {port side} and put a new taper on them. Valves stem protusion is the same as the 1999-2004 TCs 1.990-2.024 very important. What ever you cut off the heads ,make a 'alum.washer' the same thickness for the comp.releases.