So what are the differences in the pre '87 heads and the post '86 heads? (besides the centerbolts) I was looking to put some pre '87 heads on my TBI. Also what is the best chamber size? is 58cc the best for a 305 TBI?

well depends on the casting you are comparing to
I believe 87 and up heads also went to guided rocker arms so if you are looking at swapping youll need to get some unguided rocker arms (hint: crane and summit sell stamped unguided 1.6 rocker arms for around 65 bux)

you are probably looking to swap from casting 187 heads to 416s which are probably the most common head before 87 which came on LG4s and L69s

the major difference is in the intake port where the 187 heads have a swirl ramp which severly hinders flow

I believe most 305 heads are in the 55-58 cc range and you definately dont wanna go bigger than that. The smaller the better.

btw i did just that, im running the 416 heads on my car

Okay thanks Pablo I think I'm gonna go ahead and swap these heads. I'm gonna buy some nice 1.6 roller rockers from summit for these heads. So if I do this swap, everything will work out when I bolt it all up?

there is one bolt hole that wont be there for the passenger side accessory bracket assembly
you dont need a bolt there the outer and upper bolt is enough to hold it in place so dont fret