Block ID?

Your block is from a '75 and newer. You can narrow it down by finding the date code on the right side or the code stamping on the top of the block on the right side between the coil bracket and the head. The first digit will be the year model, then the engine size. From what I've seen, the '75 and newer heads all used tappered seat 1/2" reach spark plugs and no plug tubes. It's interesting that you have a '69 exhaust manifold on it....