Will this kill my 904 ?

No offense but your problems are exactly why one switches to a glide. Let the convertor soften the launch and if needed tune it with convertor pressure if needed. The low gear first is too much for no rear suspension. I've also got a buddy with a slingshot running a blown Buick of all things. He uses the pulley size to adjust the hit. That's after bending the chassis on a really tall wheel stand. He's got a BOP TH350 in it. Weight wise, cost wise, a PG is what you need.