Hi Baz- keep yer 'ookas' to yerself....
When you say 'early '50's, I think Plunger frame (up to '57), if so, I can't see a later cover being compatible. If it's a early swingarm ('54-'58) different story, Folk with swing-arms may be more knowledgeable...I think there's a couple of different ones after '58, but I'll stay out of it