Re: Anyone using a PRS stock on a RRA LAR-8?
All you need to do is set the cheek piece to the proper height for your setup, measure (2x) where you need to cut, mark it off, then take a Dremel cut-off wheel, sander, etc. to it and relieve the riser slowly until you have what you need?
If you still aren't comfortable doing it without pics, try ARFCOM. IIRC, there is a 30+ Page thread on the RRA LAR-8 and various "issues" with the rifle. I am SURE someone over there has brought this issue up at least once and pics may be available. If not, try posting your question there and see what you can reel in.
If you do finally decide to do it, you can always do a step-by-step pictoral with directions on getting the PRS altered to properly work with the LAR-8.
Good luck!