Sorry, but it is nothing like a Lee-Enfield. I should know as I own one in .303.
My guess is a foreign make, as I've not seen anything in past American historical arms that look anything like it. Definitely a "trap-door" design, but its not like any Springfields I've ever seen either (I also once owned a 45-70 Springfield).
Something that interesting might be worth a letter with accompanying photos to the NRA's magazine, "American Rifleman". Their staff is quite knowledgeable when it comes to odd finds in the firearms world. I'll do some more research in my own books to see if I come up with anything.
This site will show you what a Lee-Enfield looks like:
http://www.rt66.com/~korteng/SmallArms/leenfld.htm





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