Transmission angle?

[SS454]

OK, I'm ready to put the T56 in my 70 Chevelle to check the fit on the newly modified tunnel and to get some measurements on the crossmember. With the motor and trans bolted together and bolting the motormounts to the frame, what angle should I be shooting for, and where do I measure this at, the tail shaft or maybe the shifter plate? What angle should the carb plate be at also? I hope these are'nt stupid questions.