halyard winch on mast

[windfall]

I wish to thank those members who have taken time to respond to my question. I have found the discussion helpful and will certianly look to see if more replys are offered. The boat owner has sailed with me on my Tartan 37, with mast mounted winches located pretty much as Brian Duff mentioned, and he has found halyard work easier than deck mounted winches. Note: His Saber 38 has halyard winches mounted aft and to the outside of the mast 3-4 feet from the base of the mast in about a 45 degree angle from centerline. He does not have halyard winches in the cabin top in the forward cockpit. I intend to mount the winch on a stainless plate formed for the job by a New England spar builder for this spar section and winch. I have information to keep a separation with plastic between the plate and the aluminium mast.
One detail I have seen on mast mounted winches is a downward cant of a few degrees presumably to prevent overrides, my winches are mounted square and do not override but since this is for a friend, would a wedge under the winch base be necessary?

Thanks, Sam