1983 280sl

Hello, anyone have experience changing engines in early 80 sl's? A friend has a 1983 280sl 5sp that is tired. We were thinking that a motor from a 300E would drop right in and that the existing 5 speed would probably work with minor modifications. We want to use a single cammer for simplicity and cost reasons. I once did see a 300SL in 1990 when I was in Essen so I know the motor will fit.

Any comments? What could one expect to pay for a nice low mileage engine?

Thanks,

Carl