hamonic balancer hitting
In all my life I have not seen a passenger-car damper that fricking huge, lol. I have no idea how you are gonna make all the belts fit, and still fit a fan on the pump........nevermind the clearance issue.
My guess is that, that engine is not/never was, out of an A-Body.
I only know A-Bodies and I know there were several styles of Timing covers.
The earliest had NO timing marks but had a little metal strap tab bolted on.
The next bunch had the cast in and raised boss, sometimes on the left and sometimes on the right. Of these, some had the seal installed from the inside, and some from the outside. On one of those, the seal boss stuck out further towards the balancer; and I think it was the one that had the outside seal.
If it was my 360, I would search for a more common A-body balancer and matching cover, that fit just like the 318 balancer except it has the 360 weighting on the backside, (they are marked for 360) and much more attractive pulleys. That beast you got is a monster.
Be aware that your monster damper may not be weighted the same as the P-car damper, and that would be a sad day for you, cuz it would require rebalancing your stuff.
Happy HotRodding