Search for Project Binky on You Tube to get some jig ideas. Two guys in the UK who build and race Rally cars stuffing a Celica AWD drivetrain into a 1980 1000cc Austin Mini.
Some good ideas on fabricating jigs for installing bits that, while in this case are putting an unoriginal part in, the basic concept and approach is very useful. Plus they are very entertaining and very talented.
Their jig can even function as a rotisserie.