You can use a williams rack and column, with the pipe work disconnected. But you still have to allow the air / remaining fluid to travel from one side to the other of the rack (as the middle is sealed to allow the rack to work under normal conditions).
If you want to run a subframe mounted engine you must use a r19 rack as the pipework allows the rear engine mount to fit (or you can 'modify' a williams rack).
If you use a 1.4 / 1.2 manual rack, you need to use a 1.2 / 1/4 column as its longer.
For the alternator, you can either get an idle pulley like the cup cars or use the set up off a volvo 440. Just go to the scrap yard find a volvo 440 and remove the bits you need which will be the bar that holds the bottom of alternator and the bracket that hold the top. Tp fit these you must remove the tensioner and pas pump with its associated bracketry.
As far as i know, i was the first person to theorise about running the williams rack with no pas steering as a manual rack after testing the speed of the rack against other racks. Winston was the one who tested it for me in the illy, and to be honest it works better than the manual rack set up as its actually easier to turn when fitted. Ive now run one for many many miles and have had no problem with it what so ever.
I kept a small amount of fluid in it and sealed it but piped it so that the air and fluid could still circulate.
On a rally car even the williams rack can be a bit of a handful on hairpins, so the 1.4 rack would be a bit slow to use. If its a track car i would go for the 1.4 rack as its lighter, mechanically simpler and you wont need the full lock like you will on a rally / sprint car.