Last year I fitted lecky windys to my dads xr4i(1982), to replace the manual ones.
As far as I can remember the holes are the same holes used for the manual regulator, I think I might have had to drill 1 more hole, but other wise straight fit.
Do the wiring first, or just use wires to motor and when you get it in a certain down position it will go straight in, you do not need to change or move the clamps holding the window.
tabetha