The other week I was at the local Sunday market, and I came across this heater tap, from??? As the BB had had the heater tap leak all over my distributor, and I had replaced it with a generic one, that doesn't want to turn off the heat, I purchased it. Cheap enough. It is vacuum actuated, as it comes, however, this was easy to remedy, by unscrewing the actuator.
As bought

Without actuator

Using some copper plumbing capillary fittings and a base, made from ¼" steel, I soft soldered up a fitting to go on the motor. Now, the tap was for ¾" hose, so the I used a ½" to ¾" elbow, with short lengths of ½" and ¾" tube, for a hose to attach to.
Fittings

I reused the cable clamp, from the original heater tap. Never throw anything away, eventually it becomes useful.

After soldering the base to the pipe work, I painted it to match the engine, and made a mock up of how it will be installed, next month, when I have the engine out, to check the clutch.
Mock up