The following listings are various interchangeable parts for the BMW 1602 and BMW 2002 from 1968 to, but not including, the two-barrel 2002.
BMW Air filter:
Purolator AFP 50, Fram CA189PL, Lee AFL 132, Apco AA 189, AC A132C.
one piece N Bendix EC-18, Borg-Warner A-518 or A-520; two piece N Borg-Warner A-500.
Standard-Thompson (NAPA) 140.
BMW Gulp valve:
BMW Fan belt: Goodyear 13T 344, Texaco 316
BMW Air pump belt: Goodyear 13T 315, Texaco 307
These are generally for emergency use, since the V-shape is different.
BMW Fuel Pump Rebuild Kit:
In general, stick to OEM or Bosch components, but it's good to know that there are other things that will work if the need arises.