[ctandc]

Depends.

What cc are the 350 heads? What’s the stock head gasket thickness?

Most 305 heads are 58cc combustion chambers. The majority of the TBI 350’s would have 64cc chambers. That’s all taking into account a previous owner hasn’t swapped stuff around.

If this is the case, adding the 305 heads onto the 350 will raise your compression ratio.

Just google how to measure the cc’s of your combustion chambers. Not expensive or hard. Well worth it.

Next google “Quench area for small block Chevrolets” and do some reading. Again, nothing but time and a few simple tools needed.

If it were me I’d check the 350 out before deciding on anything. Were you losing coolant? Was it mixing with oil? Was it burning coolant?

I do know I’ve bought more than my share of 87-later 350’s with “blown head gaskets” or “cracked heads” and they all turned out to have a leaking intake gasket.

Hope this helps.