Those Huskys aren't too far off from their original designs from Cagiva, when was that, the1980s?
We had a 09 WR125, boosted to a 144 with Eric Gorr porting for top end. Ran great. Suspension was pretty awesome with just proper springs.
Our current "old" bike is a nearly new 1999 KTM 125SX with new gen forks, shock, wheels, brakes and proper valving for GNCC. It does everything very well. It is a rocket too.
If you want the latest development in a mainstream 2t, the new KTMs are it. Bottom line though, the rider makes a bigger difference and a well tuned and fresh older bike can compete. Our 2002 380SX was competeting at a very high level last year and was far too much motor for tight hare scrambles. After the holeshot it was a bear to deal with. That rider is on the old 125 now.
Last time I checked, the WR Huskys were on the list of approved street legal bikes in NJ.