I removed the OEM thermostat and replaced the O-ring. It required ingenuity with adapters and a full range of spanners and sockets. Before I put the housing back in place, I took new stainless hex fasteners, ground grooves in their theads in the first 2 or 3 thread forms, some WD40 or similar and ran them in and out of the block threads. A poor mans chaser for the threads. Why? I could run the bolts home when putting the housing back in place (no thermostat) withy fingers and do a final torque tighten.
I used an inline thermostat from the guys on the Rover75 site. Their thermostat OD is adjusted to make it fit into the hose more readily.
The engine warms so fast that I have hot air through the heater so quick I cannot believe it.
I think I am 20,000km into this mod and I recommend it. Sumer heat on Austrian passes and extreme cold in Hungary and Germany.
