Is it Fig. 7-7, as in my Bentley?? "48-398" is shown in a box on the figure in my book.
First, center the rack per Bentley.
I would suggest using the split line on the ball socket, between the flats and the round part of the tie-rod socket.
And also the inner (closest to rack) edge of the mounting bushing location on the aluminum housing. See the "white" area in the figure just beneath the rack gear.
The adjusting of the outer tie rod, during alignment, will make up for any small differences. You want to make sure that the socket has full contact and good grip on the rack end. Some folks put red locktite on the threads when re-assembling.
Anyway, that's what I would do.