Re-engined with R-1830, DC-3A/C-47A type cowling.
The GR-1820G107 was a commercial/export version setup for a turbosupercharger and roughly
equivalent to the R-1820-65 used on the B-17B/C/D/E/F. The "civil" versions had a 100hp lower
power rating than the military versions, however there is reason to believe that wasn't actually
true. The R-1820-93 that was used on some B-17F was a 1,350hp engine.
The turbosupercharger installation on the B-24 might be a guide to adding one to a Buffalo:
Of course you'd have to fit it into this: