I have fitted a high mount to my standard GU winch bar, (with out cutting the top out), It took a lot of work but all worked out in the end,
this is what I did, after lots of research , I came to the conclusion that it needed to run backwards to be mounted on the original mountings, from this I looked at getting new gears cut to allow the brake to work correctly, but the cost of this was just not worth it, (Giggle pin UK) were the best priced and very helpfull.
So after someone from this site suggested that I could turn the winch around it would reverse the brake direction,(cheers) . As high mounts are a bottom spool winch, and a standard GU winch bar needs to top spool the rope.
So I stripped the winch and got some mounting feet welded to the back of the main lower case, modeled of the other side,
On the top case I had some weld added so I could redrill the motor mounting bolt holes to allow the motor to be rotated at 90' , This was to clear the top as it was very close, still had to cut the back lip out a bit to get it in.
I reassembled the winch and made a cradle to bolt the back bolt holes as well, and then made a winch release leaver to suit,
This was a lot of work but it is tidy and works well
( this winch pulled me out of the Jarden river bogged to the axles with the camper on the back, single line pull in soft sand)
Here is a couple of pics of my assembled winch.
http://www.youtube.com/watch?v=5yKDCL6Gz7k
EDIT:
post fixed up
Kingy