Being from the "Trick the Hell out of it" school, I hate to be a bubble burster but I think you are chasing your tail. The current AFM presents no significant airflow restriction. I dont have a source at the moment but I recall the restriction being somewhat less than 1%. The air flow sensor plate is already about 25% larger than the throttle body. The engine will run out of airflow well before the meter becomes a choke point. Since the relationship between the plate and funnel represents the fuel demand of the engine attempting to fit the larger meter is likely to only yield significant tuning headaches without gains in power.

__________________

90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff