Thank you for letting me join. I am building a 68 Formula S Cuda, started on a rotisserie and now getting close to finish

I am building a 68-340 for install in my 68 Formula S. I have completed {or so I thought} the build. The engine is in the car but I have snapped 2 oil pump intermediate shafts. I installed a new bushing, new shaft/gear and new oil pump but still snapped 2 shafts. Any help will be appreciated.