Magnum mount issue?

My 340 was a 70' date code and had a forged crank so the balancer is for an internally balanced engine, the professional products balancer flat out said what to do incase of neutral balance engine that had been rebuilt as such.

The torque I was told was ok for use behnd the engine as it had come off my 340 as well..... Starting to worry this will cost a lot because I have been driveing it trying to iron bugs out with no luck.