Lets have a go at estimating the time to completely strip an original Black Shadow engine, well worn with remnants of original paint. This will include a total strip out of all bearings, oil pump sleeve, and whatever spindles that fall out............Whatever preparation you consider, so that the cases and covers can be completely re-painted in a high gloss enamel/euro- thane finish to concourse standard. This includes all the time to carefully mask it up for paint prep.........then a total careful reassembly, with near all new parts..........Bearings, spindles and oil pump sleeve installed before the paint job of course. Rebuilt crank and rods, new pistons/barrels if necessary, all new case though studs, nuts and washers. New cams, followers, timing gears, heads fully overhauled with new guides, valves, springs, rocker bearings/pins as required. Replace the output shaft bushes, perhaps a new gear or two in the gearbox, replace half the gearshift mechanism, and perhaps some of the kickstart ratchet components. Rebuild of the primary and original clutch.......New chain, tensioner blade, ESA springs, seals in the primary cover and bushes/seal in the chainwheel............repair the clutch shoes, worn pivot bores, and plunger bores.......!!!....... New pivot pins and toggle links, carrier bush, new friction plate, springs, etc................It goes on and on............New oil feed/return lines and fittings as all the originals are all mangled and bent per usual..........Plus carry out any sensible upgrades to stop oil leaks and/or other improvements to aim for a reliable and reasonably oil tight engine.............. Oh , and don't forget all the accessories, overhaul the carby's, magneto, generator.............all done to as close to original as you can.............Ok you can fit new 289's, plus and Alton, and a new BTH or similar............Just to make life a bit easier for you. Don't forget too that the cases will almost certainly need some machining repairs as well........... So Ok lets all have a good guess at how long this should take if you were doing this full time.............
..............Good luck.