If it feels as sweet as a nut to the red-line and that it'd rev forever - it's the Jag engine! There was a batch of LR specific AJ-V8s which had incorrectly torqued bottom ends - but it should have gone bang by now if it was one of those. As Datatek said they don't take kindly to LPG. I've put many. many faultless miles on AJV8s (probably something like 250K) - never had one miss a beat and I thrashed the cars mercilessly - they happened to be fitted to Jags. One of the world's best engines ever - early (non LR) ones had a few teething issues but they are pretty bullet-proof these days. Of course any engine can go bang if servicing is neglected, they are thrashed cold or you're just plain unlucky!
As a note I thought there were two capacity Jag engines fitted to older Jag L322s, 4.4 (na) and 4.2 (Supercharged) - of course they used the 3rd generation 5.0 AJ-V8 from 2009 - but I don't know what they're like - never driven one.