Not sure what Reba fork you've experienced but they are an air fork with alloy uppers, as far as I know they have been since they first came out. I've had many, still have some, they are pretty much a sid in all honesty, and I've got a few sets of them too. You can actually use a straight CSU from on a 27.5 set of lowers and change the air shaft and rebound to compensate for the longer lowers and bobs your uncle, a. 27.5 Reba with a straight steerer. You'll need a longer rebound adjuster dial too as the void in the lowers is longer.
I'm talking solo air, but the same is possible for dual air, and depending on your travel needs, you might just be able to get away with removing travel spacers on the air side to compensate for the longer leg (if they were reduced that way from factory as some were).
I'd take a Reba over an sr fork any day