Many thanks to Terkaa for his article http://forum1.aimoo.com/Dodge50/TECHNICAL/DIY-Remanufactured-Clutch-slave-cylinder-1-2206491.html. I would have added this info on it, but he forgot to add the tags so as to be able to find his article in the future.

Terkaa suggests boring & honing the lockheed slave cylinder out to 24mm & then using an "Isuzu Bellett PBR 4515 clutch seal". Unfortunatly they stopped making the Bellett in 1975 & nearly all of them were sent to Austrailia ! So, no new seals available here in UK/Europe.

Fortunatly the hydraulics people , Derek Lane & Co, Whitestone, Exeter  01392 811466 sell a similar sized seal. It is part number SU24-14-7DI-P & costs £4.87 +p/p.  The outer diameter is slightly larger than the original & will fit a bore up to 24mm.

If your bore is really rusty, you can ream & hone it out to 25mm but the larger seal that they sell for this has an internal diameter of 15mm (which is larger than the original & so you will need to make up a new "piston" on your (friends) lathe. The piston will be the same length & overall shape, but have an outside diameter of 24.8mm, a 15mm diameter recess for the new seal. The recess should be 8.3mm wide.) I do not have the part number for this larger seal (I forgot to ask. nor, sadly, do i have a lath (or friend)).

For a suitable reamer (for this job & the kingpins) try something like the one i use,a Cyclo adjustable reamer 23.81-26.98mm TL07830: http://www.ebay.co.uk/itm/190745542869?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D190745542869%26_rdc%3D1#ht_2643wt_1314  £26.

For a suitable honer try the Sealy VS029  http://www.ebay.co.uk/itm/Sealey-vs029-Cylinder-Hone-Kit-4-in-1-/110992992974?pt=LH_DefaultDomain_3&hash=item19d7b2aace#ht_1055wt_1093  £18.

UPDATE:

I have covered about 4000 miles now & have not used/lost a drop of clutch fluid since the HONING.

(Master brake cylinder next !).