I broke an output shaft at 700 horse at 3350 pounds.
Some guys get lucky, some don’t.
The fact is, the stock parts are 50 years old, they can break with pretty much any decent power. No way of knowing.
To the OP, seems like square peg round hole. Sensible thing is to go to a glide that can handle the power, and make the car way more consistent.
It’s never gonna be a world record holder, being consistent, not breaking and having fun seems logical to me