The above image shows a useful solution for the ring sets.  The 100mm rings that hold the FS-60C are attached directly to the Parallax rings that hold the FSQ.  A small modification had to be made to the rings since they will be shipped with a tapped hole at the center.  No riser blocks were required.  

R100    $69 + S/H

R125    $69 + S/H

R150    $69 + S/H

 100mm, 125mm or 150mm  guidescope/finderscope rings with  3/8" aluminum adjusting screws with large 1/4" Delrin Tips.  Stainless steel and anodized aluminum throughout for maximum durability.  A perfect idea for mounting guidescopes to large Dob rocker boxes or existing OTA tube rings.  

 

The rings have three 1/4" x 20TPI holes.  One centered on a 1.25" flat base and the others .5" from center (1" apart)  

100mm guidescope rings include .5" riser for added clearance.