Help date an L-50 - late 40's - early 50's?

[CamWilde]

I inherited a pawn shop find from my dad when he passed away last year (he bought it in Galveston, TX in the 80's). I'm sure it's been stripped and re-varnished (ugh) because even though I don't know much of anything about Gibson archtops, all the research I've done so far shows that this was likely originally a sunburst AND I can see a couple of varnish drips on the back.

 

What I've got so far:

I'm pretty sure it's an L-50 since it's got the trapezoid markers.

The top looks like unlaminated spruce so that tells me it's an L-50 as well.

It LOOKS like there was once a paper label because inside the bass side f-hole; it looks like some residue/clumpy dust areas in there.

I found the FOM (is that right? What does that stand for?) number under the treble side f-hole but the number is pretty much illegible (26 is all I can make out - see pic)

I'm 99% sure the tuners aren't original simply because they're missing two screws and it looks like there's no screw holes in the wood behind the holes. I haven't removed them yet, but plan to and replace them with some that are closer to the originals.

The logo is either painted or a decal (I think paint) with the dot in the "i" touching the "G".

The pick guard is new (it didn't have one when my dad bought it; I replaced it).

 

Based on research so far, my best guess is that it's a '49, '50 or '51. Anything else I can look for that would narrow it down?

 

Thanks!