I assume they converted it to an "O" from an "IO" for simplicity sake. I think all the fuel tanks are in the wings, so no pump needed at all with the carb engine. No need for return fuel lines w/a carbureted engine. Only the later Pawnees were injected, earlier were carbs.

If the entries & paperwork were complete on the O-H, I wouldn't think the lack of an original engine logbook was too big of a deal. There is now an engine log, just doesn't have the starting history. Though it doesn't list the "dash #" of the 540, I think most of them were acceptable engines.

I've flown 250hp Maules, but only stock Super Cubs.

Also...I'm not an interested buyer.