Ahh, that 190E 5.0 is awesome!
Probably is one hell of a sleeper.
I think the most common engine conversion, amongst the tuner community
is the Supra engine.
Typically I see them cranking out (a claimed) 400-500 HP, if not more.
If it cost less, parts are easy to come by, and can crank out more HP,
I wouldn't care what engine went into my vehicle.
I always like car shows where they open up the hood and there is some monster of a twin turbo engine
cranking something outrageous in HP. No mater where it originated from.
My favorite video
BMW M 536 Turbo. 700+hp! VIDEO
When I lived in California I used delivery oil to a popular BMW mechanic/racer, Bill Arnold.
He built a nice sleeper for a customer. It was a 1990-ish 318i but with a 95 M3 engine in it.
Looked totally stock until you challenged him on the freeway and GOOD BYE !!!.