How long should shaft bolt for predator 212 be ?

Hey there Im rebuilding my mini bike and I have a torque converter and I lost the bolt that goes into the engine shaft. know that the bolt is a 5/16 24 but i don't know how long it should be for a torque converter set up. Does anyone know?
I guess I wasn't thinking about what is common. I used a 1-1/2 SHCS because I made a counter bored washer/retainer so it wouldn't stick out so much, and give me more room for the TC cover.