Don't remember KTM having black forks in 1984, all the ones that I have seen on 84's were silver, super easy to check, just get the stamped numbers from the top fork cap and the front wheel appears to be a Z spoke Yamaha unit that has been grafted in. I have had these forks in 2 of my pre85 bikes and there not a patch on the 43mm conventional forks that were originally in place. Forks aside, the big issue that KTM had with the USD fork with a drum brake (and the same issue I've got) is that you can't get a "safe" routing of the brake cable. Come of a decent jump and the freek'n brake cable gets caught in the front wheel. Have a look where the last stay is on this bike, it's attached to a flimsy fork guard and it's way down on the fork. It's a a country mile up to the first guide on the front plate. Plenty of room for the cable to bend and head towards a rapidly approaching knobby tyre!
Bloody nice bike, although I'd expect a sprocket guard for the expected $'s