If you install the 2.3 MSG tranny make sure you (1) use the 2.3 clutch & flywheel, or (2) use the 2.6 engine plate (or two 2.3 engine plates stacked) if you use the 2.6 clutch & flywheel. The 2.6 clutch & flywheel is larger & thicker than the 2.3 setup, the larger clutch will contact the MSG bellhousing unless the tranny is spaced backwards a bit using the thicker engine plate(s). You also need to use the 2.3 throwout/clutch release bearing and clutch arm and the clutch cable housing needs to be secured to a bracket as in the picture. Even though your engine is a 2.3 this stock clutch cable bracket may have been removed.
A quick tell on which clutch you have: 2.3 disc is 8.5", 2.6 disc is 9.5" in diameter.
'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, body ROUGH, bought new 12/4/78. A pre-P'up?
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch.