I'm thinking about buying a 1975 Chevy 250 from a guy, and I was wondering what the differences are between the '75 and the '68 250 I have in my truck. I've read that Chevy started putting on an "integrated head" in 1975. What does that mean? Will my Offy intake fit on an integrated head?

Your Offy intake will not fit the integral head. The intake manifold and the head are cast as one piece on the integral heads.

Thanks for the info. Will a non-integral head fit on that block?

Yes, it will bolt right on.