To be honest, there just aren't many gaskets out there for the Rover V8 these days. The 'Generic' ones are most likely from Bearmach like the rest of them, or possibly by Payen, which is a division of Federal Mogul. Heck, my Payen gaskets all had Rover part numbers stamped on them, so I suspect they may actually do the manufacturing for LR. I used a set of Payne gaskets in my 3.9, and they have honestly held up better than the original ones did.
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.