No personal experience with V8 pumps but I recently just installed one of these UK made Marks Water Pumps for my 200TDI. They were the OEM manufacturer for Land Rover for many years (likely what was on your truck new)
"JLR may have ceased production of the Land Rover Defender with the last one rolling off of the production line in 2016, but Mark Water Pumps certainly hasn’t stopped making its vital components. The company, which supplied the original equipment water pump for 16 years from 1990
has been checking through its aftermarket back catalogue and has established that it can still supply water pumps to cover an amazing 43 years of the vehicles 68 year history."
"The Pro Flow range of automotive water pumps is manufactured in the same factory as the OE pump, so design, quality and availability is assured. For the Defender range the following are available as OES parts"
Mark Water Pumps Limited MWPL announces replacement water pump availability for 43 years of the Land Rover Defenders history - Mark Water Pumps Limited
These are the same pumps as the XS Pro Flow line distributed by Britpart. I had to go direct to Marks for my 200TDI pump because Britpart doesn't carry it.