Its a little late, but if you want to check your geometry I highly recommend spending some time playing on
www.bikecad.ca. When I built my bamboo bike I was trying to mimic my Cannondale Synapse while staying within the basic confines of a Hero bike kit. Changing lengths and angles on the computer is a whole lot less stressful than trying to do it on the fly. The free version doesn't produce a full scale drawing but the owner will email you a .pdf of your design and that can be scaled up and printed. I just drew one on a large piece of paper with a ruler and a protractor.