I have a pair of 88 305 TPI heads I want to port as rhuarc30
is doing to the 350 heads. Do the 305 heads have the same
intake and exhaust ports as the 350's?

Is the combustion chamber too small to use on a Vortec short
block? I believe it is 9.5-1 compression now.

 

You might be able to get the 305 heads to flow as much as stock L98 heads but I dont see what the point would be. You cant put as big as valves in the 305 heads because of clearance issues and the 305 heads have a 58cc combustion chamber as opposed to 64cc on the 350. This will bumb your compression ratio up but you should still be able to use pump gas. IMO just get yourself a pair of stock 350 heads and port those. You'll be much happier with the results. Hope this help.
Latter Barrett

 

I don't know about what they flow but, mine are my 305 tpi heads and they have 1.94 valves and I could have gone larger. the valve are will need to be unshrouded though. and as for how mine work I take other 350 tpi cars with similar mods with there stock heads.