Quite possibly - that's a seven speed Maillard freewheel with a 13-21 range, by the way.

I actually did try it with a 7 speed Suntour freewheel (13-28) but the jockey pulley rubs against the largest cog. I haven't spent any time adjusting it to see if I can get the configuration to work properly, though.

Thanks for the suggestion. I'll experiment with a couple of freewheels but in the worst case this bike may end up in the retro roadies thread with SRAM Rival.