Orignal 225 ??

got a question for the experts, I'm going to swap motors on my late model year production 1961 Lancer. The one in it is just wore out, honestly I've never seen any thing run, let alone as well as it dose (as long as you keep the plugs clean) and smoke as much as it dose. The block casting no. is 2202857-8 I think this is a very early 225 and it was painted silver I just thought it was a rebuilt one but could it be the original motor?
Larry