I own a '52 LG-1 - a grand guitar. Looks like it went through the Korean and Vietnam wars, it's so pock-marked. Just dropped a harmonica case on it, to add another insult to injury.

I believe the banner headstock vanished some time in the late 40s (never seen one), plastic bridges came in round about the early 60s (late 50s?) Not aware of an LG-1 ever having an adjustable bridge.

Gibson numbering was notoriously difficult to work out, last time I looked. But it can be done. Trawl the net and you'll find the info.

These are seriously-loved guitars. People bang on about LG-2 etc., but I've played some of those, and personally I can't hear or feel much difference. Except price. No doubt I am open to contradiction on that.