Yeah '49 crankcases, '49 frame, the top rear unit bracket has not been cut away to accomodate the 'jampot' units.
Already got the superior SR maggy fitted. plus later full width hubs, and maggie cover from late '50s.
Throw the genny, fit a bantam tank, fit Carey cams, 9:1 Willis piston, "p" off those stupid hairpin valve springs, then just be gentle with that useless early Burman 'box and you will have at least double the original 23 hp!
Memories!!
cheers pancho.