The number i found on the block is 3970014

On the head 8786389x i think.

 

You shoul'nt have any trouble matching them up in here.

http://www.mortec.com/

 

Going by mortec's #'s you have a 70-76 350 with either 2 or 4 bolt mains. The head #'s you posted might be incorrect.
What part of the head did you get those #'s ?

 

The 014 block was made later than 76 I suspect; I had a 78 Z28 with one. It's yerbasic 350 block, nothing special one way or the other; 4" bore, etc. I don't know why people get all concerend about what casting their block is, as long as it's whatever bore and journal size they were led to believe when they bought it, about 99.99% of the time it makes no difference whatsoever.

Go ahead and build it. As long as it doesn't have either of The Problems, where the starter bolt holes are drilled too far from the crank which makes the starter produce that awful grinding noise and turn the motor slow and gets worse when you shim it; or the lifter bores aren't pointed straight at the cam (both very common for SBCs of that era); life will be good.

 

Aren't some of the older blocks stronger due to higher nickel content?

 

Would that make any difference at any power level than most of us are concerned with (below ~450 HP or so)? Not really. So it's not worth worrying about in most cases. I'd be alot more concerend about whether the starter worked, than the lore about which blocks have higher nickel content.

Check your head casting number; 3s have a strong tendency to look like 8s. The first digit in the number you posted should almost certainly be a 3 for example.

 

Yup..the heads are..

3986339X...71......307/350......74cc chamber

Ah well. The only reason i got this engine is my 305 is toasted..and i have (now) 5 days to move. Only going to be a 3 hour drive..after I get there the 350 could melt for all i care =D