First issue might be that the compression ratio would drop a LOT, since the 350 heads are sized for 350 cubic inches of displacement versus 305. That is a BIG difference, that would drop the compression into the anemic range.
You would have to mill the head a LOT to get that amount of dispplacement difference compensated. I don't know fi you could do that without other problems, like interference between pistons and valves.
I don't know what other issues might be encountered, but I would think the compression ratio loss would be a disqaulifier all by itself.
Jim G
