Clutch spline Question

[AirborneC10]

I've got a 1970 C-10 and I have another motor to drop in it.

I need to order some parts - namely the clutch.

I got this far in my search on Summit:

http://www.summitracing.com/search/P...evrolet+clutch

but now it's asking for disk diameter and talking about the number of splines.

Now someone will say "remove the motor and tranny, split them, and count your splines" and normally i would do that, but I am borrowing the cherry picker and need to have the old motor out, split, the tranny attached to the new motor and back in the truck in a weekend - which means I need to have the clutch ready to install when I remove the old motor.

So can anyone help me choose the right clutch to order?

1970 Chevrolet C-10
Motor: Chevrolet 350 I bought off Craigslist
Transmission: Original 3-speed column shift tranny.

Or am I going to have to split these first?