The low pressure regulator was made in two versions. The recon kit must be bought accordingly. But a CNG kit will fit an LPG car and vice versa.
Again, a regulator form a LPG Transit or a Vauxhall, both fitted with Necam back in the day will fit a CNG car. As the previous post, it's the high pressure stage that is differs, not even present on LPG cars.
P1 cars don't have a temperature gauge. Not sure if thsi applies to P2 cars. P1 cars get a fuel gauge in their place. I've installed a Scnguage permanetly wired into my OBD2 port. Sits under the trip odometer. Menas I have permanet scannign abillity too and it looks neater thatn fitting any aftermarket gauge.
I ripped the idea form thsi guy. Mines the smaller, cheaper version of the Scangauge, and I've rerun my OBD2 port under my dash using the wiring from a breaker.
https://www.youtube.com/watch?v=Nj34dakoayM