Gotta love GI ingenuity, or Marine, for that matter!
I can give you a few details about the Stinger, and I have a friend who has done some research, but in general, here's what I recall.
Off the top of my head, (and my copy of Small Arms of the World has gone AWOL, currently), I think you may have the cyclic rate a bit too high. Or, at least for the parent gun of the original Stingers.
While I don't have the exact details (maybe I find them, later, eh?), the first reports of a stinger type conversion came from Guadalcanal. And the base guns were Browning .30 cals from wrecked aircraft. But it wasn't the fighter planes guns that were used. Some Marines took a few of the Browning .30s from the wrecked SBD dive bombers, the flex mount rear seat gun (originally a single, but later a double gun mount). Supposedly, because it used a manual trigger, but just as likely because it was what they could get. The fixed, electrically fired .30s from damaged planes would have been grabbed by aircraft armorers, to keep the working fighters shooting.
Those guns were (most likely) Browning .30 cal M2 aircraft machine guns. (not to be confused with the .50 M2 heavy machinegun). That gun has a cyclic rate of 1,000+/- rpm, about double the infantry ground version of the .30 Browning (1917/1919 variants).
There were only a handful of these guns, and were completely "off the books". It created a very useful weapon, for certain situations, being the lightest belt fed full auto available, and with the highest rate of fire. The Marines found a use for this, even if it was frowned on by various commanders, because it wasn't something the Corps provided.
One commander is said to have ordered his battalions to get rid of their stingers (after the battle was over). But the idea had taken hold, and enough of the men who knew about them had been spread around, so the stinger just went into hiding, until the brass looked another way. Until it was needed again, and then a few came back, and more were made, when the chance presented itself.
There been some good articles and research done lately on the Stingers. Really good use of available resources, in spite of the "official" attitude of "if its not issued, its not for us". As far as weapons went, anyway. OF course, the guys in the field did what they had to do, in spite of the "attitude", and especially when supplies are low and infrequent, as was much of the Guadalcanal campaign.
I haven't heard of any field mods like this from ops in Iraq or Afghanistan. It possible there haven't been any, because we have lightweight high volume firepower much more readily available to our ground troops. Remember that the Marines landed on Guadalcanal in Aug 42, and the majority carried 1903 Springfields & a few tommyguns. But they had water cooled Browning .30 cals! Look up what they did on Bloody Ridge.
The official military establishment is still very "down" on troops modifying weapons (that work, if it don't work, have fun), very "officially" restrictive about troops having their own guns (although some commanders are much more lenient than official policy), and they are very down on "war trophies" compared to WWII.
With the level of coverage in our modern ops, I think if there was some kind of useful, needed modification on the scale of the stinger, we would have heard about it by now. You might consider the changes made to M14s (stocks and optics, mostly) as mods, but since they are using manufactured parts and are more officially sanctioned. But not like the stinger, it was, litterally a bootleg gun, seldom were two exactly alike, field made parts for the conversions.
One of the more fascinating things to come out of WWII is the eventual shift in doctrine and attitude between going "by the book" and "start with the book, then do what works" in military operations planning.
