Looking for my first CZ match chamber PRS Setup (none in stock)

[boxhitch]

I found an MTR for about $1,100 but it has the 16 inch, and I think minimum of 20 inches would be more ideal for longer range?

I'm a pretty decent shot at 50-100 yards with my CZ 452 American.

no reason you can't run the 452 in a match and see what its about
while it may be entertaining to do mind games while trying to find or build some special thing, participating trumps all

Most PRS Rimfire is not considered long range imo, take a look at a NRL22 c.o.f. and there may be a target or two @150-190 yds, most are well under 100. It doesn't take much to shoot 100