23 Spline

whatever you do, don't do what I did which was to make the U-joints the weakest link; that did not end well.

I sorta wonder if you won't actually have less of a problem than I do, because you will never need to rev it way up and sidestep the clutch like I did a few times. But I found out real quick, that was not necessary; because my 367 with BFG/Cooper 295/50-15s broke the tires loose at less than 2000rpm, on a soft launch.
In the end I made the clutch disc the weakest link. And that was about 4 discs ago,lol, Maximum endurance was about three summers maybe four.
No big deal, my record is 17 minutes to take the trans down, on a 4-post drive-on hoist. and that includes dropping the pipes/mufflers, shifter, and the GVod.
discs are cheap. Well at my power level they are, lol. Mine usually spit the springs out and crack the hubs, only one started to loose the linings. They vibrate a long long time, telling me to get my azz in gear. Not like a U-joint that fails catastrophically, and the flailing driveshaft makes a mess of everything, and then yur walking.
Whatever you decide;
Happy HotRodding