inpepinnovations@aol.com, here is the data on Rega Arms given their standard mounting distance at vinylengine.
http://www.vinylengine.com/tonearm_database.php?make=Rega&sort=manufacturer&ascdesc=ASC&type=1&pass=null&Search=Search
http://www.vinylengine.com/tonearm_database.php?make=Rega&sort=manufacturer&ascdesc=ASC&type=1&pass=null&Search=Search