If you can, get a copy of Bruce Canfield's "Collector's Guide to the M-1 Garand and M-1 Carbine." He covers all of the marking made by all of the manufacturers. He also gives dates an d serial number ranges and the like.
If you are looking for a shooter, it's very likely to have all sorts of maker's marks on the parts. In fact the larger the variety, the better. In military service, all of the parts were interchangeable, so the armorers at each level--Battalion, Regiment, Brigade, Division, etc.--used the next part in the bin.
It is only now, in the richness of all the parts we have that a person can get replacement parts that match the maker on the receiver. Which, when that gets on GB or a show, suddenly adds $4-600 to the arm.
You kind of have to go with your gut if you are deciding between a couple carbines of similar price. I'd probably go with the best looking metal, rather than best wood; carbine stocks are just too easy to find. I'd be biased towards te flip-up "L" sight, but I'd also rather have the lever safety/push button magazine catch combo versus the button saftey/button mag catch.