sure sounds like a nice find. a quart every 300 miles is not normal consumption. but, if you look at the manual i wouldnt be surprised if it said a quart every 600 was. that is what it said for my 1962 190c. 29 mpg sounds good for the mileage. i would drive it with a good oil such as rotella 15w40 for a while and shake out the oil consumptio issue. it may be less with modern oil. some will recommend synthetic, but i would not use it in something that old unless it had been rebuilt and maybe not then. i believe that you will find any mercedes wheel will bolt on up til at least 1995 or so and maybe later but i only have personal knowledge of up til 1990. i had a 1972 220. shortly after that they introduced steel sleeves and life of mb diesels went up dramatically. i dont know about gapless rings. personally i would use factory rings in a rebuild. i have owned prob about 20 mb diesels through the years, most with lots of miles.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.