Rega plinth measurements?

On another but related subject (to Audiomods 6) can anyone with a Rega turntable tell me what the measurements a) and b) are in my sketch?  The context is that in specifying my PTP Lenco plinth I've ended up with the tonearm too far forward for ideal antiskate setting.  The only measurement i paid attention to was the 222mm pivot to spindle distance.  I can get round this issue by toeing the arm inward toward the platter so not a big problem for me, but i'm communicating with someone who is commissioning a plinth based on mine from the same carpenter.  I would like to help them both.

Many thanks Frank.

Yes, that would be an easier way to measure. The fact that tonearms vary isn't particularly relevant, because all I'm trying to do is work out where Rega thinks the best place is to mount their 222 mm spindle to pivot arms.

ICL1P wrote: Many thanks Frank. I too remember all that stuff about the squaw sitting on hippopotamus hides, which tells me that if a) = 200 mm then b) must be 96.35 mm, which is rather more than your measurement.