Does the choke valve assembly mount on the 2 carburetor mounting screws on the OS 48 FS engine? If so is the spacing of these mounting screws the same as the carb mounting screws on the OS 52 FS engine? I would like to adapt a choke valve to my OS 52 FS engines. Thanks.

There is no choke made by O.S. that fits onto the FS-52 Surpass. With modelers tending to use electric starters, they eliminated the choke because it's not needed if you use a starter.