I had a good friend with an 81 28' with the Isuzu turbo. In the early years Airstream added the turbo upon installation, it was not an Isuzu turbo. That fact resulted in a broken oil return line from the turbo to the engine, blasting all the oil out and destroying the engine. Now, I have never heard of it happening to anyone else, but be aware it could happen on the add on turbo's of the early years. There was about 100k on the engine when this happened.
He replaced the engine with another crate Isuzu which had a factory turbo unit on it as delivered. No problems with that one.
I would not be scared of the Isuzu at all, any year. Just be aware that the oil return line might be a thing to replace on a non factory turbo one. Otherwise the engine is virtually bulletproof. And noisy... grin.