The Lex AFM is a 7M-GTE specific mod... 7M-GTE uses a KVAFM (Karmann Vortex Air Flow Meter), 7M-GE uses a VAFM (Vane Air Flow Meter)... and not one Toyota Supra ever used a MAF (Mass Air Flow) sensor.
The only real options you have are: a) a full standalone EMS $$$$$$, b) MAFT Gen II and a GM MAF, or c) a MAFT Pro and whatever type of air flow measuring system you want. None is simple or cheap. The standalone will be the most expensive, then the MAFT Pro, then the Gen II. You're going to need to tune the new management system so either count on shelling out for dyno runs and tuning or add a wideband such as the LC-1 by Innovate Motorsports to the list as well... the wideband is recommended as all three of the systems I listed are capable of integrating with it and will help track the AFRs and it helps monitor for serious problems.
Don't bother trying to build a beastly N/A... it doesn't work out well... trust me.
You'll never break 300RWHP and even getting there costs a fortune. The 7M is a crap N/A platform... if you want N/A drop in a 2JZ-GE or a V8.