I have heard that 350 heads will not fit onto a 305 without getting the cylinder bores punched out, on account of valve interference with the cylinder walls. Is this true?

Considering as how plenty of factory 350 castings are 1.94/1.5" valves, they (valve sizing) will fit.

Whether or not it's smart to put 350 heads on a 305 is a whole new matter.

I have a pair of heads from a 327 that have 2.02' Intakes. I suppose they wouldn't fit.

In most cases, there isn't a problem.

But, you should limit valve lift anyway. The biggest issues are valve shrouding by the cylinder wall, and chambers too large for proper compression ratio.

Bump so as not to start my own thread.

I'm going to be putting 350 heads on my 305. I'm assuming I should get head gaskets for a 350? Is there going to be a detonation problem at all withe the 1/8" ((4-3.75) / 2) mistmatch all around the circumference of the cyls?

Are you kiddin me? With that whopping 7:1 compression ratio you are going to make, there wont be any problems with detonation!

Most of the gaskets are the same. For some odd reason a few of them are listed 327/350 only. Havent figured that one out yet, I guess I better go look for water in the oil of all the 305's Ive used 350 gaskets on.

I guess If you were to use 64ishcc heads and flat tops the compression wouldent be too low on a 305, sure would idle smooth with 7:1 compression.

Hey, it'll run on the cheap stuff! lol!

305 LB9 heads = 58cc combustion chambers
Aluminum LT1 heads = 54cc combustion chambers

My compression will go up...hopefully to 9.8+

Thats the truth!