412 Diff Ratios/Gearing Upgrade

[peasantslife]

Hello all. I'll just introduce myself - a medium term owner of a 412 S2, since 2001. Bought as a running but rotten smoker...I ran it solidly through the first winter, then we gutted it from lockers to rear wheelarches and up into the roll hoop to put back metal. Of course with so much damp for many years all the trim was shot, so took a Rover 800 Coupe and 'installed' trim (not quite finished but useable). I now alternate use with other classics and neo classics Aston/Rovers/Triumphs. So the Bristol is asleep in France at the moment and I'm in the UK. My next projected enhancement is to improve driveability by diff ratio swapping...3000rpm not required for 70mph....So, looking in my Owners Handbook I see possibly 2.88 or 3.07 may be fitted. I'll take a stab it is the 3.07, but short of the ratio tag or actually checking by rotation is there any wisdom out there as to what was actually fitted? (I could happilly fit the 3.07 into the V8 Aston replacing the stock 3.54 - a recognised improvement on manual AMV8's), then sourcing a 2.88 from a V12 Jag (some XJS models only?). Or what about 4 or 6 speed box swaps. Any good knowledge of options? I' m not afraid of buying stateside and shipping and 'engineering' to make fit is no issue. Though probably would go Injected engine with associated box...circa 300-350bhp I dont need sprinting but want legs for better cruise refinement.