Bars are looking good! Glad you have the 5-speed, way more user friendly. The OEM key switch is cak; I have a new one in a box that won't retain the key in "ON".
Seats are tough to get right without riding on one a while. Ddavidv has a good'n, I have the yard sale vinyl version. Mine's a little soft and has a bit of a pocket, so after a couple hours it gets old not being able to slide back a bit. The leather version looks harder & flatter, both attributes which should be an improvement over mine. I'd probably go with ddavidv's leather choice to live with long term.
Leather = PART No. 91475 ; SINGLE SEAT, TRIALS TYPE, LEATHER, BLACK ; (Brown = PN# 91476) ; £125.00
Vinyl = PART No. Z91363 ; BROWN STUDDED SEAT TO FIT ALL IRON BARREL 350 / 500 MODELS ; £60.00
PART No. 92590 ; TOP YOKE, SINGLE SPEEDO ; £210 ( Speedo only)
PART No. 92591 ; TRIALS FORK TOP YOKE ; £220 ( Plain, no instruments)
PART No. 92513:TOP YOKE, ALLOY, CAFE RACER ; £210 ( Speedo, ammeter, key or voltmeter)
E-bay prices need to be way better than Hitch's. There is more risk involved as you're on the wrong end of a 12,000 mile supply chain with a low-cost bidder. Alan has more interest in keeping you happy.
Is this an AC or DC lighting system? Some LED headlights just need the proper voltage & don't care about AC vs. DC. LED is 0.2 x the draw of incandescent, so less load. You can always add a Radio Shack diode bridge if need be.
Glad you finally got to take the old girl out on a shakedown run, looking forward to more pix -
Best regards - ACR -