some ktm rads fit, some u can more or less make fit.
I have a crushed tube on my left rad from hitting the valve cover. It's almost flattened but have been running it for the last 150 hrs w/out issue. think it came off a 450 sxf. (slightly different downtube angle)
been running that same rad with jb weld for the last 40 hrs.
The aftermarket rads are alright, but rad guards don't fit.
On another note, i've seen a safari tank on a ktm 350 rub/wear through the corner of a radiator. plastic beats aluminum, go figure
And finally...some worthless info: a left rad in europe costs over 300 euros new. and that's just a few hours from ktm headquarters.
I would consider having someone at least try to fix it locally... for a spare.