Careful with changing the tyre. Only fit the recommended width rubber on any given width of rim. A 110 will be plenty. Yes 120 may be better for braking grip, but not for steering if it's "pinched" into a triangle on a too-narrow rim. As
this page shows you, on a 3" rim like you have, only 110/70-17 is recommended. You could use a front wheel off a firestorm for a 120 tyre, but it starts getting more work and money.
I think the braided lines will look nice. I wouldn't change them unless they're too short (they probably will be). They won't be worth much s/h, maybe £20 on eBay if in decent condition.
The problem for me was the length of the clutch, choke, throttle cables. I could change them for longer but that's more £££ and hassle as they'd have to be custom made.
Up to you which riser to go for, just check that your cables will all reach first! Don't overplay the length of the forks. At free length they'll be maybe 1 inch shorter, but they have so much less sag that the actual ride height will be about the same or maybe even higher.
Worth trying the caliper bolts you have. You can get away with a bit of extra length, as long as it's never going to touch the disc! Pinch bolts were cross compatible on mine, should be on yours. What else are you missing? I will rummage in my spares box for you, no promises though.
The modified yoke I have would come to you as a pair with a standard lower yoke for £25 posted. Just remember the lock boss has been removed.
I think you have the same idea I had for making a better clocks bracket. Potentially much tidier than how mine is but as you say, no good with a welded yoke! I was thinking I might use the funds from selling you a pair of yokes to get an unmodified early yoke, and make basically what you are talking about. It's annoying that I can't use the unmodded yoke I have, but it looks awful with the flat-bottomed risers overhanging the curved surface. Fine with single bolt fitting risers, but then they're no good for me...
