rubber overdrive

Reaching out to the community for information, guidance, and advice. So here's the back ground of where I am now and what I would like to do possibly: Start point 1974 FJ40 F.5 J30, 4.11 diff, 31.10.5R15 tires - Upsized tires to 235/85R16 - Replaced J30 with 81 FJ60 H42/34MM split transfer case...