A mechanical gauge is going to have a fairly long lag compared to an electric one. OEM Manifold Air Temperature gauges stick the thermocouple out into the airflow for fastest response.
Some of the digital gauges will read a MAT sensor; the cheap ones use the VDO/SW style temperature probe originally designed for water temp. The heavy brass jacket would make it too slow to be useful for monitoring the inlet temp.
Are you planning to leave the temp gauge on the car permanently, or will it just be for help while tuning?
FYI, if you're using an intercooler, put the temp sensor downstream of the core; for tuning you're primarily concerned with temperature at the carburetors, not upstream where the turbo is. If you're planning on track days, note that once the intercooler is thoroughly heat-soaked it is much less efficient than when cold.
FYI2; the early Esprit Turbos used blow-through Dell'Orto DHLA 40 or 45 carbs. I'm not ept enough to compare Dell'Orto and Weber naughty bits, but the factory Lotus jetting for them is here:
http://esprit.driestone.com/index.php?p ... arburetors and might give you a useful starting point.
FYI3; for all the dislike some tuners have for blow-through, the factory setup on my Yamaha Turbo worked flawlessly for 40,000 miles, even when I cranked the boost up from the factory 6 PSI.