I can't really offer advice beyond my engine except that all the compression ratios from the 1972,73 P Spec Manual reads 7.5:1 - 8.5:1
the 10 BTDC initial / 35 max from the RS 004 works great with carbs and 8.5:1
your comment "(10 ish compression?) " means your dealing with a max advance around 28deg, probably
you need more advice than I can offer
