They may bolt up, but will be too long and hurt the handling of the quad in my opinion. At 16.5" the trx450r shocks are a full inch longer than the raptor 660 front shocks, which actually gives close the correct extended and compressed lengths with 22" front tires with Fullflight a arms. With 21" front tires, the yfz450 front shocks would be good, which are 15.75" long. The yfz450 front shock is the longest shock I would install on +2 Fullflight A Arms.
If you were to use the trx450r front shocks, you would have two issues.
1. The quads ride height in the front would be insanely high.
2. Your tierods will bind with your upper a arms. (Mine do a little with the 660 front shocks at full extension if you turn all the way one way. With another inch of travel, you risk bending a tierod).
I'm not saying you shouldn't buy these, (do what you want, it's your quad) but yfz450 front shocks are a better shock and much closer to the correct length. You could run the trx450r shocks with the Diamond J relocation kit, but that's a waste of money then in my opinion.