Hi all,
Here’s a little about me from my intro post:

I grew up with my Dad taking us camping, hunting and fishing in a 1992 Nissan Pathfinder XE. Most of my favorite childhood memories involve that vehicle and he sent me to college in it. I took my wife on our first date in it and went all over the mountains of Idaho in it. Long story short it means a lot to me and my family and I want to keep it running a long long time.

In a few years I’m going to be in a place financially where I can really do some work on this truck and I want to surprise my dad by either restoring it or majorly improving it. It has always had a very wimpy motor and terrible gas mileage. I want to keep the cabin exactly as it is, every scratch and dent has a family story behind it. But I’d love to make it into a safe, efficient daily driver and back roads wanderer.

I’d love some advice on whether it would be crazy to drop the cab onto a newer frame, regardless of the make and model. I’d love to get maximum performance and efficiency.

If that is not feasible I’d consider a frame swap with another pathfinder or an engine and tranny swap. I’ll be saving up for this for a little while and really would love to surprise my dad with it. Let me know what you think!

Ps I’ll post some pics of the beautiful beast when I figure out how

Well, the R50 and R52 Pathfinders are unibody chassis, so you can't use either of them. The R51 has a frame, but it's completely different than a WD21 frame and I've never heard of anyone doing that kind of swap. I would imagine it would take a lot of fab work and I'm pretty sure the R51 frame is longer.
An engine swap would be easier, but it all depends what you want to put into it. The easiest would be a VG33E swap, but that's not going to give you a whole lot more power that what you have. Next in Nissan would be a VQ-series V6 swap, which definitively has more power, but requires swapping the ECM and wiring and merging that wiring with that in your 94 model. The VQ35DE and transmission out of a 01-04 Pathfinder would probably be the easiest. The later, VQ40DE and RE5R05A trans would be a bit more difficult for several reasons. They do make engine conversion brackets for a small block Chevy for the Hardbody trucks, which should work in your Pathfinder, if you want to go with a non-Nissan option. Anything is possible where there is a will and a wallet!