Colyn:

I pulled two inertial reel seat belts from a van and installed the inertial reels down above the floor between the wing carrythru and the aileron  brackets,  one on each side.    I use the same pivot points that the regular seat belts use.  I would say that they saved my bacon during my Las Vegas ground accident in 2003 although they didnt prevent my head hitting the sunvisor (5 stitches worth).  (There were + 6  G's and -  3  G's on the meter after the accident so it could have been worse)

The only problem with my installation is the angle of the belt running from the floor back to the pivot point  makes it a little difficult to comeup thru the upholstry at exactly the right angle to prevent the belts dragging on the upholstry.  ( O.K. my upholstry guy solved the problem).  Anyway, I did see another plane where the inertial reels were inside the upholstry directly below the standard pivot points.  Made a better looking job and saved some belt dragging problems.

To me, inertial reels are the ONLY way to go.  Good Luck,  Bill Hogarty