It depends if you want original parts in which case it's E-bay or if you decide to uprate to modern parts (like I do with my old uns) in whish case as long as you avoid black components you'll be fine fitting modern bits.
My Raleigh Equipe runs a 105 rear mech and a 53/42 outboard bearing crank (105 Hollowtech 2) without them looking 'wrong' but the wheels have old Maillard wide flange hubs (reconditioned) laced to modern rims with a 6 speed screw on freewheel (to avoid having to 'spread' the rear stays)
Mind you it still looks old due to having a Brooks B5n saddle, brake levers with the 'suicide' lever extensions, cloth bar-tape and a Carradice Camper Longflap saddlebag fitted along with SKS/Bluemells mudguards but this is about its 4th incarnation as I tend to swap parts between my frames or fit parts to a different frame (newly acquired) as I want. I may end up changing the crank to an Ultegra triple Hollowtech 2 that I've got in my workshop (shed) but that will mean swapping the 105 rear mech to a medium cage one (currently fitted to my 531 Worksop Raleigh) but only if I decide to reconfigure the Equipe to a more 'touring' set-up.