I've only built 2 baleen bellied bows myself, I think John has built a few also, he started using gemsbok horn afterwards, great looking stuff. I just basically build a bamboo backed bow that is around 10-15# lighter than I want it to end up being, then add the baleen or horn to the belly, its some amazing stuff and is very strong in tension, I've found that when taking material off the belly for weight reduction I use a cabinet scraper, seems like any kind of rasp would always lift or tear splinters in the stuff. I also used EA 40 smooth on for glueing it to my core wood.
JD