While looking for inner 38-40t inner rings for a TA 3 pin crank on that pervasive site, there was a listing for short TA crank arms, 155 or 160 mm .... You might look.
I bought a take off set of 155 mm Bulletproof cranks, a while back when my son was just graduating from a 24" wheeled bike to a 700c. They worked well till he shot up in height.