This week I met a Sturmey Archer collector in the area who has a Viner bicycle with what he calls a Sturmey Archer "ASM" hub. The hub is an ASC modified by replacing certain internal components with corresponding parts from a FM hub. FW hub parts can also be used. The result is a 3 speed fixed gear hub with wider ratios than the ASC hub. I haven't heard of this approach before.
Paul Patzkowsky Longmont, Colorado