I'm still working through a couple of parts issues/choices, but here's what the build spec is looking like:
FRAME: Potts Brazed MTB #SP 11-83 052 [a]
FORK: Potts Type-II [a]
HEADSET: Specialized Channel-Lock 1" Silver
STEM: Potts Flat Bar for Stubby [a]
HANDLEBAR: Potts Flat Bar w/Potts Shims [a]
GRIPS/TAPE: Magura Ergo w/CC mod (repro of WTB mod)
BRAKES: WTB "Swiss Cheese" Rollercams, silver [a]
BRAKE PADS: Mafac 5-Bump
BRAKE CABLES/HOUSING: Jagwire (logos removed)
FRONT BRAKE CABLE HANGER: Suntour Head Binder HL-3000, Silver [a]
BRAKE LEVERS: Magura Black Perch / Silver Lever [a]
SHIFTERS: Suntour Power Thumb Shifter [a]
FRONT DERAILLEUR: Suntour Cyclone Mark-II
REAR DERAILLEUR: Suntour ARX
DERAILLEUR CABLES/HOUSING: Jagwire (logos removed)
FREEWHEEL/CASSETTE: Suntour Winner Ultra 7sp 12-32
BOTTOM BRACKET: Press-in w/spacer, circlips [a/b]
CRANKARMS: Sugino AT 175mm; Sugino 15mm Bolts [a]
CHAINRINGS: Sugino 46t / 34t (double); Sugino CR Bolts
CHAIN: Sedis Sedisport
PEDALS: TBD (Suntour BMX or MKS BM-7)
+ WTB Toe Flips
+ Speicalized stainless Toe Clips, Size L
+ Alfredo Binda Extra Toe Straps
HUBS: Phil Wood 100/130mm [a]
+ Campagnolo 1010/A Dropout Adjusters
HUB SKEWERS: Phil Wood Bolt-type [a]
RIMS: Araya 7X 26x1.75
SPOKES/NIPPLES: DT 14ga 4-cross
TIRES: Specialized Hardpack 2.2
TUBES: Modern; Schraeder
SADDLE: Avocet Touring-II
SEATPOST: Campagnolo Super Record 26.8mm
SEATPOST BINDER: Suntour [a]
BOTTLE CAGE(S): Specialized 6.2mm, Black
OTHER: NG Chainstay Protector (repro of WTB)
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(a) = items original to the bike just cleaned up as best as possible
(b) = exact replacements of original items too rough to re-use
Pretty much everything else is a best educated guess at what would have been there in 1983 based on the owner, where he acquired the bike and how he rode it. The one big exception is the tires, which probably would have been Snakebelly's or Stumpjumpers.