Many poeple have changed to the 4.0L from a newer jeep with good results. That is as close to stock as you can get without using the same 4.2L. A stroker is probably the next closest to stock. Others have done many other engines from fords, chevys, jeeps, etc, etc.. But those don't fit your criteria of staying basically stock. Search around here, and you'll find all kinds of information on swaps
As for suggesting one, I can't help there. I haven't seen/helped with any in person, and it really depends heavily on what you're looking for.
"Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life."
1990 White YJ TBI350, SM465, NP231, SOA, RE 1.5" SOA springs, Ford 8.8, D30, 4.10's, JBConversions SYE, XJ shaft, Bilstein 5150s, jb4x4 steering, MORE SS brakelines, 35x12.50 15 MT's, '95 YJ Brake Booster, '78 Grand Marquis MC, ZJ Prop. Valve