Lee
- the oil drain could be welded onto the sump directly if you dont know the info on the drilling of the return. say -12 AN or bigger welded onto the alloy sump
- Oil feed - look at the fittings of your turbo, find if a restrictor is needed, then drill and tap according to what you need, there is nothing really stating that you need a specified size, we just use what the block has since there is no choice.
- Torque settings can be the standard of your donor motor, 26 or 25 i believe are the same - look for an R33 engine manual through google.