741 case; 7290 LARGE U-joint yoke???

I think you may need to just check the splines - if the pinion is coarse spline, I think it will work. Just a note though - the 741 has a 1.375" pinion and the 742 is a 1.75" pinion. Coarse-splined 7260 series yokes do exist though, I once pulled one from a swap-meet 742 case with 2.76 gears. Not sure if that helps.

Here's an 8 3/4 guide: http://www.dodgepolara.com/rear.txt

Why not just drive it and see what happens? Are you running slicks?