you need to re-post this in the “Vintage Karting” section.
I don’t understand your question about ‘converting’ to centrifugal clutch….it appears to have one already on the engine. (or part of a clutch)
It is definitely NOT a shifter kart….it is a fairly old ‘laydown’ road racing kart.
It would require restoration by an experienced karter in order to be safe and/or actually run again.