Small block Chevy heads

[mstudman]

I'm thinking of putting the stock iron heads from my '69 Nova's destroyed 307 on the new 350 replacement block. The new 350 block will be .030 over. Will the combustions chambers on the old 307 heads need to be re-worked to match the bigger diameter 350 30over cylinders? I already figured the heads will need to get redone anyway with new everything and probable have the deck surface machined flat.

[PWMAN]

I don't know if you realized this, but you're in a Honda/Acura section of the Forum???
Anyway, to answer your Q -
the 307 heads have much smaller chambers that 350 heads. So your compression is going to be much higher. 307 heads have 54 CC chambers, most 350 heads have 72 CC or more chambers. 305 heads have 64 CC chambers for the most part.
307 heads on a 350 will suck cuz they don't flow as much air, unless you have them ported and machined for bigger valves. It should have 1.72/1.50 valves, get them machined for a minimum of 1.84/1.60.
But it would be worth buying Vortech heads from JEG's for 500 bucks fully assembled, but you also have to buy a intake manifold to fit the special heads. They flow very well for a 350, and come with 1.94/1.50 valves, probably a 50 HP increase over the stock 307 heads. Oh and the Vortech heads are 64 CC chambers.
What kind of pistons does that 350 have? Flattops or dish?