---

Just to finish this thread. The kit from Mercury contains a "sender" that one replaces the existing blank with, and a length of hose - easily enough to reach the old pressure sensor hose, and various fittings to connect the hoses up (the new hose is exactly the same diameter. A few tie wraps and the job is done. The "sensor" threads come precoated with some sort of red stuff which is I assume is a sealant, hence I didn't use PTFE or anything else.

The pressure readings are about 50% higher across the RPM range than with the old engine. Probably due to both the Command Thrust lower unit, and also 11 years of corrosion and wear on the old engine.

Thanks for the help.