I put 2.76 in my cuda with a 383 auto 727 14'' tire and it turns the tires over with no problem. But this is no race car and does great on the highway.
I run a 742 center but the problem I see here is that it was taken apart by a rooky, there should be a little back lash between ring and pinion or may have torqued the crush sleeve tight on the pinion, pull ring gear out and spin yoke