Sady's right a turbo motor is very different, the pistons are oil cooled for example. You could find a good used turbo 617; but you need to figure out how bad the rust is before you commit to, to much work and time. A rusty car will always be a rusty car, and very clean good running rust free cars can be had for $2k. Heck BHD just bought a very nice 300D for about $2,500.

Anyway start by changing all of the fluids and filters to get a baseline. You will also want to adjust the valves. If the engine has not been run in a few months do not just turn the key and crank! Pull the injectors and put a little oil in each cylinder first to lube things up a bit. Also crank with the stop lever down to get oil pressure up and oil moving.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200