If the OAL is 26" and the barrel length is "at least" 16", it's still a rifle, no matter what it looks like.
Check out the BATF paper dated July 25, 2011. That's what I go by. I keep a copy in my range bag just in case there's ever any questions.
Any measurements shorter than stated and you'll have to deal with the BATF and get yourself a Tax Stamp.
My rear grip SP in built on a Savage Model 10 "lefty" repeater. Right hand has control of the grip and left hand works the bolt and feeds ammo.
That same "lefty" action is used on one of my bench rest rigs. Mounted on a Whidden V Block (as is the SP) and fitted to a "right hand" thumb hole BR style stock.
Two screws and the action is out and ready to be mounted in which ever stock you want. Swap barrels and bolt heads as needed and you're ready to go shooting.