A set of stock Chevelle 250 Towers for the same year should bolt in. You may have to drill a hole or two but I think they are already there.
If the engine didn't come out of a Chevelle you would also need the brackets to bolt to the block and the proper mounts.
The towers/stands out of a 250 powered Chevelle from 68 to 72 should work. I think Pontiac used the 250 as it's 6 for the Lemans in some of those years also.
