I have a '92 with the 3FE, and yes it was underpowered when I bought it. A few things really woke it up. I bought mine for $5500 bucks, and it was in great shape, with alot of Toyota services recent.
-new starter
-new alt
-A/C work
-new radiator
-new tires
The 91 and 92's have 15" wheels. Because of this I was able to find some nearly new 32"BFG AT's (traded for the new 31's that were on the truck), and some 15x10 MT aluminum wheels ($275, they weren't even a year old). Try finding a cheap set of 16" wheels...
I've been spending my extra cash (over buying a newer 80) on front axle rebuild, Yakima roof rack, stereo, speakers, rebuilt rear axle, new 4:88 gears (no lockers yet), new power steering pump. rebuilt d-shafts etc. Lots of maint. stuff that you will run into on either vehicle. The '94 usually has more expensive maint repairs like the HG etc.
With the 4:88's and the 32" tires, that really measure closer to the 31"es. The 3FE has plenty of power. The shift points match the trans, and I can easily run 95 MPH right around 3100 RPMs (right in the 3FE's power band), with the roof rack and faring, bikes, A/C on, hills whatever. I can run the cruise all day in the hills with no down shifting at the posted 70MPH speed limit. The 4:88's should be a mandatory addittion when you do the axle rebuilds. Since your going to add lockers, may as well do that too. I'd be willing to bet the 3FE with 4:88's and some 33" tires would be even Steven with the newer 80 with stock gears and tires.
I also added some good brake pads up front, and will rebuild the rear brakes soon. I might just throw on some discs back there too ( weld on brackets, calipers from a Chebby I think will work).
I'm stickin' with this 80 for the long haul. The way fuel prices are going I'll prob do a diesel swap when the 3FE gives up (I'm at 184000 miles right now, I expect 300 easily).
I have $4000 additional bucks over my purchase price. $1100 of that was a result of back-ordered aftermarket Birfs, when the front axle was torn down. I ended up buying the newer stronger Birfs from Toyota (thanks to CDan's discount it wasn't more). So realistically, you could do everything for $3500 and have it all done by a mechanic (not at the dealer though).
I'll be adding the goodies soon, as the budget builds back up. But in the mean time I have an excellent family hauler, that gets about 15MPG, and has plenty of power, and looks pretty darn good.
I like the 3FE for it's strength and simplicity. They don't call it the Tractor for nothin'. Some simple improvements, including the expense of regearing, has the better more reliable engine right in the ballpark with the newer model 4.5L that has that stinkin' aluminum head. I'll get some hate for that statement, but I'll ask any of you to drive my truck the way it's set-up now, before you put your foot in your mouth... you bunch of 3FE haters...

Don't forget I do Love al Y'all, even you 4.5L mugs.
Would I purchase the older model over a '94 year? Yes I would.
I think the '94's did have the first gen airbag only for the driver. Airbags are nice, but try explainning to your wife, that she's ridin' shotgun with out one, and your sittin pretty with the only airbag...
Now if you found a really nice '96 or '97 for a few thousand more with lockers, I would have to really tink about that one, BUT, that really takes some luck.
Good Luck with your decision. You've found the right board for all of your answeres, but just realize us 3FE Mugs are in the Minority.
I love Mine