360 engine vibration

Yes, 6-7 kHz is 6000-7000 cycles per second... no way your derriere is going to respond to that frequency range LOL. Your vibration range is probably in the 10-20 cycles per second range.
Yes agreed, although the pulley does have a wobble and looks to have a wobble on the inner part too? I friend of mine is going to run it up on the lathe and see how bad the wobble is, Either way new pulley on order.

whats your thought on this one? from Rock Auto. Seems to be the same part?

https://www.rockauto.com/en/moreinfo.php?pk=5430834&cc=1070435&jsn=480

My preference for using Rock Auto is I get an upfront cost for UK shipping an import duty at checkout. With JEGS I need to pay import duty when it arrives and then it gets delivered adding further time to arrive.