drive shaft length

let me know what you think i have a chevy 355, th350 and the stock 8.5 10 bolt and im pretty sure the stock drive shaft from the cutlass the 200r4 to 8.5 shaft wont work

do i need a drive shaft out of a monte ss? with a th350 and a 7.5? or is custom the only option?

its a short tail th350 outta a car. or el camino vice versa.

so itll work? hopefully im dropping the motor and trans in this week when the rain stops. so either or ill know.

how are you guys cutting these shafts? like crude sawsall and welding it back? or of the yoke to the trans. im a g body newb trying to play with what i have.