In original condition the A10 was a very reliable bike. I'd be aiming to get it as close as possible to its original spec and tolerances. Only fit recommended parts as it's highly unlikely you'll be able to find genuine BSA new-old-stock. As you have identified small end bush issues, I'd fit 'Lightning' rods supplied by Thunder Engineering as they don't have small end bushes. A big-bearing crank and thick flange barrels are better than the earlier ones but even the early ones were perfectly OK for normal riding. As stated previously, cleaning the sludge trap is essential but refitting it isn't as straightforward as it should be; you need to be sure that it is sealed at the ends and where the centre stud screws in, and the flange doesn't restrict the oil flow. A new oil pump is definitely worth considering (I find the SRM and Wassell pumps are good), and while on the timing side I'd fit a belt drive to the dynamo. In the primary chaincase I run Bob Newby clutches and belt drives on my bikes. These are far superior to the 6-spring and even the Triumph 4-spring clutch, though the 4-spring can be made to work well if set up properly. The engineered quality of the 6-spring is horrible, but even they can be set up to work OK. Using a belt drive also means you don't have to bother with oil in the chaincase, or grease in the dynamo drive. NEB also make excellent clutches and they give the option of retaining the primary chain. I would consider converting the dynamo to 12 volt and I would not fit electronic ignition. A well- restored magneto is your friend and will get you home if your charging circuit packs in or your battery dies. I'd increase the engine sprocket by 1 or 2 teeth, as stated previously, if you're not going to go for the belt drive. Sometimes, on A10 crankcases, the breather pipe has fallen out so breather gases and oil can, over time, liberally cover the back of the primary chaincase and the gearbox plates. This can be avoided by threading the exit hole ( I use 3/8 BSF) and fitting a threaded tube with loctite; then you can fit a breather tube which reaches down below the frame. I've mixed views about the A65 type anti-wet-sump as I came across one where the ball almost completely restricted the oil flow, maybe that was a one-off, but if you're doing that conversion be very careful and take advice from somebody who has done it themselves, successfully. A sump plate with a drain plug is a (necessary) improvement due to dealing with potential wet-sump issues. If you do this you'll probably use one of the aluminium kits available, then you'll need longer studs as using whitworth bolts or allen studs instead is not a good engineering solution as you can't tighten the bolts against the waist of the bolt.
