Thanks to Beexalex for the following, made life quite straight forward.
1. Place bike on centerstand (or lift or whatever gets the front wheel off the ground
2. Remove front brake cable
3. Remove front wheel and mudguard(removing the front wheel and mudguard makes things easier, but isn't required)
4. Remove pinch bolts on lower triple trees
5. Back off fork top nuts about halfway
6. Rap the nuts til the tubes pop out of their top taper
8. Pull the tubes out of the triple trees (you may have to drive a pair of screwdrivers into the slots of the lower triple trees to expand them. This is where not having the wheel and mudguard in place really comes in handy)
9. Remove and replace springs
10. Install fork installation tool (If you don't have one, you can make one out of a length of all-thread, a couple of nuts, washers, an old fork nut with the hex ground off and the socket you used to take the top nuts off)
11. Use the installation tool to pull the tubes home.
12. Replace the rest of the stuff you took off.
I fitted the Eddie Dow type dampers and progressive springs from Paul Goff, trading as Chiltern Motorcycles
http://www.norbsa02.freeuk.com/Made the installation tool as per the instructions above, worked a treat.
The TLS was from a T100 Triumph. The discussion on here re spindles left me confused but the bike breaker man said just put an A10 spindle in, which I did with new sealed bearings, and it fits fine. The backplate or lug needs building up. I chose to do the lug on the fork leg as it's steel and I've got a MIG welder. I think the possibility of distortion discussed herein perhaps overstate the dangers, after all the existing lug and mudguard mounts have already been welded on to what is a substantial steel tube. Anyway, welded and ground the lug to no ill effect.
A spacer was added to the mudguard stay to clear the grease nipple.
Brake cable needs changing. A BSA 60-2077 is nearly right, but the inner is too short and has the wrong sized brake lever nipple. Into the black arts of cable making, nipples ordered and acid-core solder - hard to find, probably illegal to sell, but available through ebay. First nipple successfully soldered and tested today!
The ride and the brakes are transformed. The surface ripples are smoothed out and the ubiquitous potholes handled with aplomb. The brakes now work in a way concomitant with modern traffic.
Thanks for all the help unwittingly given