Ian,
as I am sure you will agree, I have been happy to offer advice and answer your queries on the NA-T subject in relation to your build, clutch etc.
So I would rather hope that you will listen to what I am about to say and take it in the manner in which it is meant.
With the best of intentions, your "NA-T man" may well have completed 35 conversions, but how many of those conversions were done for himself and how many of them are still successfully and reliably running without issue?
Tooquicktoostop has owned more supra's than I care to count, I believe he is definitely into double figures now. These include everything from NA-700hp singles. He knows a little bit about these cars and I'm sure his technical understanding is certainly reliable.
You refer to your "NA-T man" as being "very technical", but with respect, until recently, he was a tyre fitter, not an engine specialist.
As Bignum said - another member who has been around on this club for years and does genuinely have VERY detailed knowledge of the cars, I doubt highly that the issue you are experiencing is down to a faulty gauge, the cooked oil would tell me that - like yourself, I am an electro/mechanical engineer by trade.
With regards to your other thread related to your clutch, the fact that your "NA-T man" is adamant that full faced clutches will not hold the power, I am afraid I am now I'm a position to inform you, categorically that he is wrong.
It's up to you, as a customer, to form your own opinion of the service and product you have received. I am sure reading between the lines that other people will do the same and draw the same conclusion as myself.
On that note, again, please do not misinterpret this post, please read it in its literal sense.
It is neither malicious, nor slanderous, but a mere honest opinion of someone outside, looking in - bearing in mind, my own car is an NA-T too and I also have experience of converting several others with friends.