Put it on ebay as a BSA paratrooper bike. An all original bike would be worth around $1000-$2000 if it were complete and original. As yours is it's near impossible to guess a value because the only original piece appears to be the frame. It would be a major project to hunt down all of the era-appropriate parts to put it back into correct form. But I know there's a lot of WWII collectors out there who would probably do that. What it is worth to them is anybody's guess. Definitely a lot less than $1000 though.