Hi, Link_cat:
Well... adding chaos to your already difficult choice, I would give a very profound look to the dropside 1622 for sale in Vilnius. Looks like they have taken pretty good care of it, from the outside and from the inside, and that tells a lot of what to expect.
As Sitec pointed before, having 500.000 km on the frame means almost nothing to these frames and engines provided that they are decently serviced.
220 HP is power enough to go on with a heavy Box, bigger tires, lots of fuel and beer, fast as needed with no big effort and thus with not awfull consumption. I ignore which engine it has, in line or V, but spares are easy to source all around. Mercedes has a reputation for that.
Greetings.
Pairoa