Do you think it would be necessary or not to use a torque strap when using spool motor mounts?

Have someone sit in the car with the motor running and holding the foot brake and see how much the motor moves up towards the passenger side when you load the motor against the converter up to as much as you plan on doing that
Decide from that and go from there

Depends on the application. Saturday night cruise car? No. 9 second, 3300#, stick shift car? Yes.

I agree it depends on the application. The Spool motor mount itself is almost indestructible. But where and how it mounts to the K frame spool mount catch isn't so tough, it will give or pull through before the Spool mount fails.

But if your spool mounts are really , really old the rubber bushing can eventually give like anything else, but the cross bolt is captured unlike the bisket type mount that totally gives way. But even old, I don't think I have seen one give way yet, but I'm sure there are some. Now the bisket types, ive seen tons give way, even new ones with stock motors that were beat on.

I had a different reason (Dart Sport 360, 727): the bigger exhaust system was too close to the floor, and rattled on WOT. Used wire braid to restrain engine movement, really helped without increasing NVH.

I run a pair of them on my Rampage and on the
P-BODY.. cant hear them at all.. sure helps
on a launch.. both cars are SB one is a 416ci
the other 395ci