Some interesting stuff here. 
http://www.cadillacforums.com/forums/cadillac-catera-cimarron-forum/130818-cant-wait-2.html
Posts 80-83 are particularly relevant, and clearly show that a manual box isn't the answer to clearance issues

Don't forget that the 1.5" engine offset is to clear the lhd steering box and ABS unit, which even then needed moving

rack should negate the engine clearance issues provided the steering column doesn't foul the exhaust.
BTW, those 'Corvette' brakes are the ones that fit between standard and AP sizes, so a tidy upgrade from standard Omega, (guessing the discs were custom made though as they had the same bolt holes as the Omega ones), although the Merc ML/Audi S4 set up ought to be at least comparable

Similar sized discs/calipers iirc

Finally from that thread, the OP has been working on the project since 2008, his last update being August last year, and that was using factory Omega V8 parts, so it might take a little while to get up and running
