That's a nice upper.
The Kel-Tec SU16C is fun as a mag fed bolt gun w/large cap mag but you do have to use right hand. Not end of the world, I do it w/o dismounting gun.
These are really fun guns but I know it will never hold up like an AR.
I've taken a number of does w/it.
+ the barrel al;ready comes threaded from the factory.
It's almost like they want you to suppress it!
http://www.kel-tec-cnc.com/su16c.html