Vintmxman while Yamaha 500 engined Aberg Replicas are desirable bikes, they don,t really go, don,t stop, don,t go around corners and are too top heavy, fun yes, good looking yes, race able not really.
The Honda version is a substantially better thing to ride in all categories, possibly not as good looking,
I would definitely consider a SP/DR/GN 400 engined version ( extremely rare) or a converted RM N/T usually referred to as a DRM.
These will prove to be the most competitive bike of this breed.
google RMH470 and have a look, to me the best looking of this class