As far as pre-Magnum 360 blocks go, many believed that the first few years of production were the best (early 70's). I've also heard up to 74-75 was good as well. If it's not gong to be something crazy in the HP/torque dept, you can get away with almost any of them. For a budget build, you could use a pair of OEM X, J, O heads (especially if you can find a set already rebuilt). You can also go with an aftermarket head that is not too expensive (RHS or the Indy replacement heads, etc.). There's a few choices out there. All depends on your desired end result and your budget. GL.