More than likely, the water pump is cavitating causing the foam.
Cavitation is where something moves through water fast enough to form a pocket of vapor. The vapor collapses as soon as the object passes or the water passes. I doubt that the water pump blades would move fast enough to cause cavitation. Most likely the water pump is mixing air into the coolant and there is something in the coolant that acts like a soap solution to support the air bubbles. It could be oil but it could be anything such as left over cleaning solution or bad coolant.
Thanks for all of the suggestions. Trying to eliminate one-by-one.
As per some Fordbarn advice, the pic shows the four plugs and the anti-freeze I use.
Anything odd about the plugs?
I think this is the recommended anti-freeze for old cars.
On the head gasket, will a compression test reveal an issue?
Would I see white smoke out of the tail pipe?
Also, I had the car out a few days ago and had plenty of power.
Thanks
Leo