I've done the brackets but not with a heated screen.

Give the age of your car you should not have to re-drill the mounting holes on the bodywork. One area to watch is the the upright bolts - these can strip the thread easily in the originals (doubt so on the SS ones).

I recall reading on here the screen connects behind the padding.

I'd diconnect the screen but this may (will?) mean taking the dash out. If you have two people I'd just switch them in situ and not remove the screen (just have somebody hold it).

Do you have new gaskets for the brackets or do you plan on reusing?

THE BIGGEST WATCH POINT IS THE THREE SCREWS IN THE UPRIGHTS. One is longer than the other two - NOTE WHICH HOLE IT COMES OUT OF AND ONLY PUT IT BACK IN THAT ONE. Or you WILL crack the screen....

Good luck.

Richard
1976 4/4 4 Seater