Dave,
A real nice runner you have there. I don't think my eyesight will work with things that small any more
Almost a couple of years ago, I knocked one up in less than a day, but a lot larger than yours. In fact yours makes mine look massive (no I'm not boasting again).
Based around Tubal Cain's porting for the Jenny Wren. If I can remember rightly, it is 3/32" bore by 1/8" stroke, or it might be 3/16" stroke. The brain cell is fading fast.
They really are nice little exercises to do. My main problem was silver soldering the syringe tube in for the inlet pipe.
John