I'm not absolutely sure that Bukh manufacture the sail drive themselves but they do have engines, from 24-48hp, sold under the Bukh name which are saildrive.
Bukh Marine Diesel Engines and Genuine Bukh Spare Parts
Don't Bukh market under a different name , Westebeke maybe, in the US ?
That said ....8 hp ???????? Surely that's a mistype.