HW19 Armboard and RB250 SetUp Questions

I am setting up a 2nd sys. and have a HW19 Mk3 and a RB250.
I will be using a blank armboard and will need to drill it for mounting. I am looking for opinions re: which distance to use of rthe RB250, 219.5mm or 222mm. I have access to a original HW19 mk3 Rega armboard to use as a template but do not know what VPI's distance was?