Kevin, found one of these blades from a long time ago and WOW it really did great on cutting the bird houses. Got them from
http://www.pozsgaidesigns.com/
They have two types a DTPGT and a PGT It looks like they are made by Olson.
Seemed to work for me, maybe you can get a sample blade to try they come in 5, 7 , 9 sizes.
jim
penquin