TD questions, motor swapping

[Diesel Van]

Long time no see. I have a 240D motor from an 83 with an adapter plate to a chevy t5 trans. What rpm are these the happiest at for 70mph cruising? My project vehicle will weigh about 3200lb, possibly a little less. I have scales, so I'll check when I get that far.

I'd rather have the one out of a 300d, but prices are a bit much around here in Iowa. Are the later ones from say, 1995 computer controlled? There is one of those near me cheap. But I do not want to deal with a computer.

Whatever i buy, I'll part the rest of it out here.