depends on the design. I got a 40#@30" bow wich is only 55" ntn. You can probably draw it even further, and the tiller isn't that good.
I've seen an osage shorty somewhere, wich was around 45" tall, drawing 50#@26" If I remember correctly.... and a gorgeous BBI deflexed recurve, wich was 48" ntn and drew 50#@28".
depends all on the design and tiller. If you make it bending through the handle, around 2" max, you'll probably get more than 30" out of a 56" bow. You can really get short with long drawlengths, but they'll get more set and shoot slower.
Nick