Two bike restoration

Wow, quick work. Did you get the frame back to clean metal with angle grinder & wire brush? Mega impressed! The 12v wires in that connector picture are regularly bodged, I think the relatively high current accelerates corrosion.

Nice work. I might try that method on my wife's 250RS frame when i get round to rebuilding it. As for fork tubes, the options are good used ones (unlikely), new (David Silvers,patterns or nos for the later bushed forks on NBs on, patterns only for the Ns) or hard chroming yours. I've done both the latter 2 on my 400s. The N's were too far gone, so I got patterns, but I got the NAs re-chromed. Not much difference price wise, although it seems to be reckoned modern hard chroming is more hard wearing than the original process. So that's £1oo plus, and it doesn't get any better with the exhaust, although you've probably got a chance of finding a decent second hand Motad 2 into 1 cheapish. A 2 into 2 is going to be £250ish for replica parts, but the heat shields for the collector box are NLA & decent used one's are expensive. I got round the heat shield problem on my 400N by using a couple of exhaust kick ups from ClassicBikeShop, which were also a bit cheaper than a collector box, but there were some issues -

honda-superdream.co.uk/thread/10031/fitting-new-exhaust-system-problems?page=4 

I've seen pictures of an SD with kick ups that have a socket at the silencer end as well so would fit the SD silencers, but I don't know where they were from

Mine were also done at Philpots, also a great job.

Paint work looks great, projects coming on nicely. There's been a few threads on tank repairs over the years. First thing is how rusty is the tank? If it's just light surface rust, an anti-rust solution should suffice, but if it's more serious you need to try & remove as much flaky stuff as possible. I put a load of clean nuts in mine & shook it about every time I walked past it, but I remember someone a while back putting theirs in a cement mixer to rotate it for a while! Then it's a bit of shaking & some assistance with a magnet to get everything out. My 250 tank still has the magnet in it after it came of the end of it's 'stalk'
As for rust killing stuff, I've used brick acid diluted with water about 50%. It's cheap, but flash rusts very quickly after draining. Others have used white vinegar, but there's plenty of dedicated rust killing solutions available, which might be better.  The first tank I did, on my 250NB, is still going strong after 7 years, but the next two weren't so successful

honda-superdream.co.uk/thread/3722/petrol-tank-repair

honda-superdream.co.uk/thread/6655/petrol-tank-woes

Tec bike parts do some reasonably priced replica shocks for SDs

www.tecbikeparts.com/products/shop-parts/tec-shock-absorbers/honda-shock-absorbers/

Looking so good!