Autotrend EFI (www.autotrendefi.com) has a bypass style remote thermostat housing that uses a BMW V12 thermostat. It also has 1 3/8" in/out/bypass pipes to match the Pantera's coolant pipes. They chose that particular thermostat because it is a true bypass style thermostat (with a bypass block-off "hat") and has the largest orifice of any readily available thermostat. It's available in a number of different opening temps too. The photo below shows the prototype unit before the in/out/bypass pipes were welded on.
If you don't want to spend that much money, you can always use an early '80's BMW 318i/320i bypass thermostat. Many Pantera and GT40 owners run this thermostat and are very happy with it. It won't flow as much as the Autotrend unit but it's a fraction of the price too.
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