you will need a passenger side drop transfer case, i know there were a couple chevys with them i think it was a 203 or 205 case, will need both driveshafts replaced or modified, not sure of length difference between them. you may be able to find a 4x4 t5 with the rhd case that will work for you.
as for the oil pan vs crossmember you will probably end up modifying both, if you have the 283 already is it a front or rear sump? i would try lowering it in as close as you can get to where it will be sitting and seee how much room you need. im not sure that there are any pics of what a completed install looks like and i havent seen it done yet.
if you are up for making a custom crossmember you can avoid that whole problem altogether and have one that fits right without messing with oil volume and such. you will also need to modify the trans crossmember and possibly add some support for the transfer case
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Luvless
1980 Mikado-Sold.
1993 Lexus SC400 my Daily
2004 Yamaha WR250F my new love in life
2016 Toyota Camry my girls ride