Is that downtube teardrop shape? Also look at the end of the toptube behind the seat tube for JMC. You might get real lucky and have a shadow. the rear dropouts certainly look like them.If so,pick it up!!
-kreep-
Dang!What a shame. Im betting that that is a JMC all day. It looks like the down tube is more round that oval. I think you missed out on a late 80's Shadow my friend..I still have my 85' JMC chrome shadow and have not been able to part with it(even though JMC is like gold to some collectors).
-Kreep-