Fellas, I used to be involved with the NCRS (National Corvette Restorer's Society) with my '61 Vette. I took the car to many meets and had it judged and I also wound up doing some judging myself. That club is definitely "over the top" when it comes to judging originality and authenticity. In fact, it eventually drove me nuts and I stopped participating with the club. But I learned a few things during those years and a few things rubbed off.
I can tell you with reasonable certainty that, as the years go by, if you have a fairly original jeep with a fairly presentable original data plate on it, that may very well wind up being something you want to keep intact and not alter too much. We never know where this hobby will wind up, but as the years go by, it seems like more and more originality is disappearing from the scene with these jeeps. It's harder and harder to find one that hasn't been Bubba-ed up or turned into a hunting vehicle. As such, I happen to believe that your vehcile will retain it's value and appreciate more if you try to maintain a level of originality, including any history you have on the jeep and/or it's data plates.
If you already have an original data plate, I think it would be a good idea to keep it that way and not have it restamped or altered. They are what they are. Even if they do not contain an inspection date, for example, this doesn't necessarily mean anything other than someone neglected to stamp it that day before they released it. As with the NCRS, a lot of information about original stamps and stamping procedures may not even have surfaced yet. The NCRS is still discovering things about engine stampings, for example, that disprove earlier judging theories that "this car is a restamp." Photographs of original stampings have shown up that indicate upside down numbers and missing letters, for example, or complete omissions of some of the information.
So, the point I'm making is, I think it might be a good idea to think twice about having an original matching data plate altered or restamped to "make it" Marine Corps or whatever.
I'd leave the original alone and you can always get ahold of one of the many brand new reproduction data plates that are out there and have that one stamped up to your heart's desire, if that's what you're looking for. They're available just about everywhere by the dozens (TNJ Murray, eBay, etc.)
What some guys do is take their original data plate and place it behind the brand new reproduction, then screw them both on. The new one covers the old one and protects it and it looks all brandy new. Or, just keep the old original with your title and display the new repro... nobody but us old fools will know the difference other than the fact that it looks WAY too new and unscathed to be original.
Just some thoughts before you go sending off your original to make it "right" by having extra things stamped on it.
Army Basic, AIT and OCS: Ft. Knox, KY (1967)
82nd Airborne Division: Ft. Bragg, NC (1968)
South Vietnamese Combat Advisor RVN (1969)
Owner: 1972 M151A2