Hi all, I am looking to run a large feed mixer wagon with a diesel engine. I'm thinking that a Mercedes car engine would be best. The mixer is run by a PTO, ~500rpm, and it needs 60hp.

So I'm new to diesel and my question is about what size engine (hp) and what rpm.
Here is a list of mercedes engines... A little Mercedes diesel engine info I found [Archive] - Cummins 4BT & Diesel Conversions Forums

Lets say for example that I found a OM616.916 - 2.4l inline-4, 62hp. At what rpm would I expect 62hp?
I would then need to gear it down to 500rpm. How much hp would I lose from inefficiency in the gearing? What if a transmission came with the engine, could I run the pto off that if the gear ratio was right?

Thoughts? Advice? Is this crazy? cause it's gonna happen, I'd like to avoid some pitfalls though.

 

Heres' a pic of the mixer by the way...