Do the engine mounts of a 1991 Isuzu trooper line up to a 350 chevy small block? Mainly can I remove a 1991 trooper engine and swap in a small block 350 chevy crate engine?

As long as the motor mount line up the engine will swap out ok but you may have to change the ECM for the truck or reprogram the one you have. In addition be sure the tranny will bolt up and the drive shafts are the same length.

POWER STEERING PUMPS FOR THE 400 AND 350 CHEVY ENGINES ARE HELD IN PLACE IN A BRACKET AND BRACE MOUTED TO THE ENGINE.CHECK AROUND ON LINE ON INTERNET LOOK UP POWER STEERING PUMP MOUNTING BRACKETS FOR 400 CHEVY ENGINE.YOU NEED THE MOUNTING BRACKET IN ORDER TO INSTALL POWER STEERING PUMP.

2300????? Huh. I though they were 1500, 2500. i could be wrong. ususaly in the 3/4 tonne vehciles, they have a small block V8. I hae seen quite often a 350 cubic inch...but, depending on your transmission and engine braket mounts, not to mention mechanic skills and fabrication abilities, you could put whatever you want in it...As i said, probably a 350 small block is what was in there...probably

just undo all the bolts to the transmission, and remove the engine mount bolts, fuel lines, some electrical, throttle cable, battery, starter,...and a few other water lines and stuff and just lift the engine out.

The 1985 Impala came standard with the Chevrolet 305 V8. All Chevrolet small block V8's from 265 cubic inches to 400 cubic inches from 1957 to about 1989 used the same block with almost no difference in the castings, so the motor mounts should fit from one block to the next. If you are trying to swap in a 350 newer than 1989, then the motor mounts are different, and you will have to have them fabricated by a local welder, machine shop, or perhaps the best, a local short-track race car driver/builder. Those guys can build anything.

nope

The 2.8 is a 60 degree engine, and the 4.3 a 90 degree engine. Meaning the bank of the cylinders in relation to the center line of the engine. If you were asking about a 3.8 and 4.3 I'd say yes you could, as each of these is based on a 305, and 350 respectively. I don't believe the 2.8 and 4.3 have the same cylinder head bolt patterns to allow correct mounting to the block. Additionally you have to be sure about valve opening clearance requirements using the larger cylinder head because of the smaller bore of the 2.8. The 4.3 heads have larger valves, and may not clear the block surrounding the bore. The chamber of the 4.3 heads might extend onto the flat surface of the 2.8 block which is an engineering no-no due to hot spots/dieseling and other problems you would design into this monsterous mating.
I like the way you think though. Chevrolet has been doing this since they introduced the first small block back in the 50's.
You are right about the 2.8 being a dud. I had one, and it couldn't get out of its own way. You might be better finding a good low mileage 4.3, and grab the mounts along with the vehicle you got the engine from. Also be sure you get the computer, and harness. If that vehicle is injected and computer controlled, and yours is not, there would be a whole nother host of issues to deal with that you don't sound like you would wanting to encounter. In that case you might as well drop a small block in, because the issues would be similar.

you can look on autozone web site and look on repair info. Here is what it says it's located. Hope this helps.

Under hood, driver side, lower engine area, above oil pan, mounted in block

a chevy 2.8 and there is also an Isuzu 3.2 that will mount up with tranny and wiring harnesses. The 2.8 is a good engine, I have 300,000 miles on mine.

I swapped mine out and put in a 350 with a turbo 350. The rear end is not posi but if that's not a problem the drive shaft will work but you'll have to get a new trans mount. you can get one from Summit or jegs. Also the motor mounts will have to be moverd to the furthest front position. Best to put the mounts in then try the engine for fit before you bolt in the trans. You'll also have to rerun the fuel line to the other side. There are some other minor mods but you do them as you go along.