Sheldon came up with those numbers through some overzealous measuring, but yeah, you will want a slightly wider than 42mm chainline for a WI freewheel, 45 is a good number but remember that everything from frame alignment to BB shell facing to dropout paint to spindle-crank interface squirm affects chainline, so .73mm or .27mm isn't worth wringing your hands over. I'd go with the 110.5 as you can also adjust it back toward 42mm for other applications.

Any reason why you're using 75's for this? I'd go with RD's, way cheaper, just as good, and you can use 130 rings. The whole rig would cost you less than the phil BB.