Hey Chris,
Yes, the NeXgen will mount the same as the Select, both front-to-back and side-to-side. The NeXgen will however mount a little bit lower than your Select. For example, most had their Medium Select Seats mounted around 9-1/4" in their Recon chassis. Now, with the Medium NeXgen, most are mounting the seat 8-1/2" to 8-3/4". The height measurement will be measured from the highest point of the seat (in the center) down to the top of the axle.
I hope this helps! If you have any further questions, just give me a call at the shop - 704-855-3165.
-James