After much study, frustration, false starts, a trip to Hutch's shop for an exchange fender, a discussion with John Healy on the phone regarding repop stainless rear fenders and a discussion with a very talented vintage car restoration shop owner, I manage to fit the new rear fender to the bike.
According to John Healy, who imports these fenders, they are all a little warped, twisted, improperly formed, call it what you will, so the are not a drop in fit. Since I probably have a good 20 hours or more into monkeying with this fender, not including the 6 hour round trip to Hutch's shop, I thought I'd provide my opinion on how you should proceed to install these fenders, if you are lucky enough to find one.
Before I begin, John said the maker in the UK, Chris something, is not making them anymore. Don Hutchinson has two left in his shop. Not sure how many others are available. Hutch has his listed on ebay.
Since the fender is not properly formed, you will need to use the mounting points on the bike frame to hold the fender correctly positioned so that you can pull, pry or otherwise reshape the fender to fit the frame.
I suggest you start with the front mounting hole. I suggest starting with this hole since the position of this part of the fender is critical as it must provide clearance for the chainguard and the oil tank.
My old fender had about 1/2" clearance from the swingarm so that point was established with a small piece of wood taped to the swingarm. With the fender positioned correctly relative to the swingarm mount and using my old fender to establish reference points on the frame, I marked the forward mounting hole and drilled it. Then with a bolt thru that hole into the forward bracket, position the fender to establish the relative position of the fender to the frame. With the rear of the fender centered to the frame, mark the holes for the top strap that mounts between the shocks. Remove the bolt at the front mount and let the front of the fender go where it wants. Using the reference marks for the top strap hole, center the fender in the frame so it is straight relative to vertical and remark the holes for the top strap. The two sets of holes marked will probably be close, but not the same. I did this exercise several times to make sure I had the fender properly aligned. I then took a carpenter's square and using the side of the fender, marked a line thru the marked holes that was perpendicular to the side of the rear half of the fender. I then refit the fender to see how those marks aligned. When I was happy they were properply located to make the rear of the fender properly positioned, I drilled them.
Next was the strap that goes over the rear frame tube. Same exercise, mark and drill. Last is the two rear bracket/lift handle bolts. Repeat the alignment exercise then mark and drill the holes.
With all the holes drilled, using rubber washers to protect painted surfaces bolt the fender to the frame. Start with the top strap between the shocks, then the rear strap over the frame and finally the rear bracket/lift handle. With those all tight and the rear of the fender straight and centers, work the front section with your hands, a piece of wood and a frame tube as a fulcrum or any other means that will not damage the fender and bend the front portion where it needs to be. It will take some force since the stainless likes to spring back. Use towels to protect your frame paint and with some effort and patience, it will move to where it needs to be.
Here are the various brackets that need to be fit in the order they were fit.
Front bracket. This the first hole you need to drill.
This shows the relationship of the front fender to the chainguard bracket on the swingarm. Bracket is casting a shadow on the masking tape that shows the fender clears the bracket.
Here's the piece of wood that established the proper spacing from the swingarm.
Here is the second bracket you need to fit and drill the holes in the fender.
This is the next bracket you need to fit.
Here is the last bracket to be fit and for which you need to drill holes.
I used a string attached to the top yoke to establish a straight line down thru the frame and to check the position of the fender as it was fit to the bike.
Here is the fender after final fit to the frame. Bolting is temporary.
Mounted fender from the other side.
Remember the rubber washers as they will slightly impact alignment and hole positioning.
Tomorrow I'll mount the taillight. Then I'll inventory the fasteners I'll need and head to Fastenal for new stainless fasteners, fender washers, locknuts, etc.