If youre after chapter and verse on Jag ratios and such, post a question or do an archive search, at the UK Cobra club site at
www.cobraclub.com .
Most high power cobras ( ie most with V8's) are built here with Jaguar IRS and theres a wealth of knowledge to be tapped.
Most Jags in UK came with a 3.31 non Powerlok (Limited slip diff)as standard ( check the tag on the diff itself to check) so if you're after a high ratio powerlok look for a XJS as a donor as all XJS had powerlok.
We have quite a few people using jag diffs with high output engines , Drag racers included, and a properly set up diff should be able to handle in excess of 500BHP regularly.
I would suggest doing a search on Jag Diffs at the UK site and all will be made clear.
Cheers,
Tony
