A couple things that I see..those KB's are a stock replacement piston, so sticking to a 1.90 intake would probably be best. The intake volume can be misleading, TW heads have the intake valve moved so runner cc will be different. With a performer intake I wouldnt go with to big of a cam, it will choke it at higher RPM. You might look at changing it to a stealth or performer rpm.
Rail type rockers are stud mount and were used to keep the rocker arms aliagned on the valve stem tip. They'll only work on valves that are designed for them with a longer stem. Pedestal mount is what they use in later 302's to keep the rocker straight, and yes, you can only use shims to adjust them. Regular stud mount rockers are what you want, the heads you get will have guide plates to keep things straight. Get a good roller tip rocker and you'll be fine.
You might go with less gear, or a T-5 conversion. 4.10's will suck of you do alot of freeway driving. Do they HAVE freeways up there?
Personally, I'd get eith AFR 165's or e'brock performers and the cam you have. I have the 165's and you can get them with a smaller combustion chamber so you wont lose to much compression.. but either one will make a bunch more HP than the stock heads. BTW is it an original 4v car?
I have a 68 coupe, but it's not really stock
