Which Dampener are you guys using?

Engine size doesn't matter. A longer stroke or heavier rods/pistons would simply mean that more weight was added to the crankshaft counterweights to internally balance the rotating assembly. The "neutral" balanced balancer/damper and flexplate should have been left alone.

You could actually use a 318 balancer on your engine if your 360 is internally balanced because 318 are internally balanced also.

As for overall diameter, it doesn't matter as long as it balances out neutral. The actual weight might be different because of the overall size, but it would balance neutral if that's the spplication it's for. But I would prefer to use a diameter close to OEM to help read the timing marks on the timing cover.