In 18 years as a mechanic... plenty. The 163 with a V8 doesnt have much room up front. Tack on another two cyls and the front of the motor would be well into the radiator in addition to the other issues already mentioned. If the op were to actually pursue the swap I'd guarantee what he ended up with would be worth even less than the sum of its parts. In this day and age 163s are crusher fodder as soon as repairs reach 4 digits.

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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