with respect Mark,The 2011 GCR state pre 65 bultaco only, that means before 1965 which means 64 models, the only pre65 bultaco metisse was a single front down tube 200cc engine.
In 1965, rickman brothers built the frame while bultaco built the centre port 250 engine, all to late, date 1965 and over, In Australia there was only a small amount of bultaco metisse being race here, and the year was 1966. I do agree that it was a positive move to make the bultaco metisse eligible for pre 65, it adds more riders to the pre65 class,where in recent years it has been lacking, its a shame it wasn`t encouraged 18 or more years ago when the vintage rules was adopted when curtain vintage riders own them.