There is NOTHING wrong with a carbureted engine. From 1991 to 1995 GM was throttle body. While this helped cold starts and altitude, it does NOTHING for performance and is less efficient than a carburetor, because it does not atomize the fuel as well. Intake manifold designs were still limited by the wet intake, so no advantage there. Ford fuel injection of the same time period was absolute junk. It was not even a closed loop system. Back when my engine had a carb, in cold weather my motorhome got better mileage than my brother's 1995 TBI pickup truck. There is no real advantage to fuel injection until they went to the high pressure port injection.
It was also in the 1996/97 years that GM came out with the fast burn heads. The combination of better head design, and port injection brought about significant improvements in HP and mileage.
As far as the trans is concerned, the 4L85e is one very tough trans. It is the same design as the old TH400 and shares many internal parts. The only limitation is that it uses a variable slip torque converter. Great design, but requires changing the fluid more often. 15K miles, max. I had a dealer worn me about that with a car I had of the same design. While there were many out there replacing transmissions in the low 100k mile range, I had 180K on mine when I sold it and never had a problem. I drive my vehicles hard, and even towed with it. You just have to change the fluid more often.
Personally, the 2 biggest issues you face with age are rust and long term stress to the shell which potentially causes leaks. Everything else can be fixed. Personally, if I were looking at the 90s coaches, I would be looking for a DP and specifically a Foretravel. Very well built from that time period. You will also find the DPs of that era got better fuel mileage than the modern diesels, due to smog requirements.
