Engine ID

With all the talk about 1275 engine identification I was curious about the
vintage of my "new" 1275. It doesn't have the engine number plate nor holes
that show it may be missing. Is there another way for me to ID this engine?
The head does have air injection provisions (sealed by the PO with
bolts/plugs). 
 
Herby
64 MK II Sprite - HRBYTOY (under construction/de-construction)
62 MK II Sprite - HRBYTOY2? (My new driver)
billh@aaai.com 
www.herbytoys.com