As Tim Koyen mentioned here above, I wouldn’t be too concerned about 450 degrees, just like he said, brand new chassis right after they were built were powder coated next.
It is the 800 to 1000 degrees that would really be a concerned
I am powder coating my Son’s OTK, as soon as the season is over, it will look pretty again, not to mention it will cover most flat spots at the bottom. LOL
Just kidding, but it will cover quiet bit at the bottom for sure.
No worries about the handling man, we have never seen any changes in chassis behavior at all.
P.S. Some times people don’t remember how to put the kart back together, on the same settings, camber/caster pills, their toe changes, their ride highth changes and that throws them off, or most of the time is just psychological.