First build

I bought a 1965 Barracuda Formula S. I found out that both heads have cracks. I was told that these can be pinned. The cracks are near the water jacket and not around the compression area.
Has anyone repaired these heads and had success, I'm concerned?
I was told that 318 ci and 340 ci heads will fit on the 273 ci block, is this a fact?
I was really hoping that I could keep this vehicle stock but have a limited budget. Any suggestions?
secondCuda705

The heads are at a machine shop at this time. He said that the cracks were in both heads by the water jacket. The thing is that I didn't have any coolant in the oil when I drained it and it didn't seem to be coming out of the exhaust when I ran it before tear down. I will call him tomorrow and see if he will send me a picture to post.

Can someone tell me how to post a PM on this site. I'm old but new at this. Thanks!