poly mounts or a mid/front plate for a body

In your case, I'd probably make some solid aluminum inserts for the spool mounts, and use a rubber trans mount (to avoid cracking tyranny case.)
My 1.36 60 ft car used a steel Hurst front mount, a steel mid plate and a rubber trans mount.
My used-to-be 8 sec car uses a front plate tied to front down bars, and a mid plate. Solid trans mount, it's not going anywhere.
You could ask @71Demon540 what he uses. He's got a 1.17 60ft 540 Demon.