I have read many posts about the oddball British pipe threads on the Smiths guages but as of now have not found that to be the case.
I had to adapt both the
oil & water senders to different locations & used stantard NPT 1/8 to 1/4" brass adapters. The 1/8"NPT thread screws on by hand & seals up nicely with no damage to the original " British " threads.
Also I replaced my electric
oil pressure guage with a mechanical Smiths guage & used a 90 deg. 1/8" NPT brass fitting on the back of the guage to connect a braided S/S line to with no problems, leaks or again, damage to the original threads.
I am sure if you try try it you will find the same results.