Brian B said:
I may have an additional SS700P in the parts stash.
There are several versions of "SS700P" headlamp (there are variations of shell, reflector and bulb type). An 'S' Type SS700P would have an ammeter, lighting switch and single (high beam) warning light. The shell you have seems to be the correct part.
Nobody has mentioned it so far, but the (red) steel fuel tank although similar in shape, is from a later Roadster. The 'S' tank would have been fibreglass (and the filler cap would've hinged in the opposite direction) however, as you may know, the ethanol in modern pump fuel will eventually eat through the fibreglass, so a steel tank is preferable and you would be unlikely to encounter any disapproval for using a steel tank from a later model.