Ive done MS on my M103 and a PCS TCU for a 722.6 behind a 104.980. If you're serious about the swap I'd just plan to do a standalone ECU and TCU out the gate. If you're going to do all the work of a swap it doesn't make sense to me to handicap yourself with electronic controls not intended to work in your setup. Standalones can be set up to work the way you want from the get go. The learning curve will be steep but the results will make you glad you took the journey. Another member is struggling with late model OE electronics in a 107 V12 swap and everything he cant get the OE stuff to do, my PCS trans controller can be set up to do, no problem.

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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