Your receiver should be fine, then, provided there's no weldment in it.
I'm a little envious of your find. That sounds like an excellent buy - seriously. Old beat-up M1s go for more than you paid.
EMcF is Earl McFarland, who was the ordnance inspector for that period of time. It sounds to me like someone did a restoration job on your rifle. It'd be very unusual to find one that had not been rebuilt and had all manner of parts on it. Either way, it's still worth great money.
One question - does it have a lock bar sight on it?
As far as higher serial numbers, I have an HRA in the other room with a 5.600,000 S/N made in 1956, so yours is a pretty low number. Still, the end of 42/beginning of 43 puts you square in wartime production and late enough that Springfield and Winchester had the production lines down to an art.
You got a great rifle for a great price. Enjoy!
Cheers,
kk7sm