I ordered a CM shaft w. billet trans yoke from Strange and used their measuring guidelines. Been a few years, but the price for everything was reasonable...well, back then.

https://www.strangeengineering.net/forms/driveshaft-order-form/

If you plan on using the same yoke....

""DRIVESHAFT ONLY – NO TRANSMISSION YOKE: Push the transmission yoke all the way in until it bottoms, pull it out 7/8” and measure center to center. This is the ”C” dimension. If you are not using all 1350 series yokes, supply the “D” and “E” from any that are not and note which end they belong.* Your transmission yoke will need to be sent-in to properly balance the driveshaft.""