Water Pump Fittings

Are you trying to use the larger bypass hose?
Some pumps have the smaller hose size threads, looks like what you have.
What is on the intake?
Ok I just looked pictures of the 69 I use to have and it looked to have the larger hose.

Two choices, bush the intake smaller and use the smaller hose or get the correct pump.

Going to work on trying to get the correct water pump. Old water pump and intake have the larger fitting. Just can’t seem to figure out where to locate the correct pump based on the unreliable info on the internet.