273 cast iron water pump bypass fitting size

Hi all, I’m due to replace the water pump on my ‘66 Barracuda 273. The old fittings for the heater hose and bypass hose aren’t going to come out and I need to know what size NPT to bypass fitting I need.
The large threaded hole in the new water pump measures 1” across and the current bypass hose on the car has an external diameter of 1 1/4”. (Air con car)
Can anyone provide me with a size? I’m not concerned with factory correct, just want to get the job done, thanks.