Looks great! I really like the bloodwood bridge and look forward to hearing how the AT-125U sounds in the bass. I've been trying to do something similar with a 6 string, but I'm having trouble sourcing a wide enough transducer (3.5-3.75").
Geoff,
You will probably have to make your own transducer. Look for piezo co-axial cable. It's cheap, and instructions for making your own undersaddle transducer with it can be found here:
http://liutaiomottola.com/PrevPubs/Piezo/CoaxTransducer.htm