My 68 3/4 ton 4x4 project

[big ass 4x4s]

im currently restoring a 1968 k30 4x4 (single wheel back axle) longbed im putting the 72 grill on it. anyway was wondering if i should keep the original 327 4 bolt main in it or go with a cummins diesel. if yall are wondering im 2 toneing it blue and white lifting it 6 inch suspenchin lift 3 inch body lift and 38x12x17 boggers. any suggestions just let me know. ill put before pics up soon of before and after pics when finished.(might be a while) also restoring a 1985 cj8 almost done put pics up of that too.