I always use the same weight BHs as FPs.
Never occurred to me to try anything else.

Swap some points (I'd change the FP since they're cheaper), and try again. If the spine is indeed weak, you'll need to stay with the lighter points all the way around, so check that first.

Once you have the same point weights, follow the Easton tuning guide for bareshaft tuning. Then, once you've got that dialed in, check that all of your BHs spin true on their shafts, tune for broadheads, and you're done.

There is still time to get it all adjusted. Just start now since you may end up getting a curve ball thrown at you, like needing to start over with new arrows, having the local shop be out of stock on the points you need, or finding out that there is a big backlog for fletching yourshafts if you don't do them yourself.

I try to get my new equipment as Chrismas gifts so that I can start making changes right after deer season. That way I'm ready for 3-D before bowfishing starts in the Spring. It's also easier and less frustrating to make your adjustments on the range when the weather isn't 95 degreesand humid.