I've done a fair bit of work today, including filling two knots one of which was then taken out as I removed more wood.
The squarish cross section has had its corners taken off on the belly to help it flex a bit more and now I've had it back to 60# on the tiller and the tips are almost back to a brace height.
The pic shows the big filled knot which will be the main 'feature' of the bow, there is a nice flush of colour, and you can just see the hairline crack from the centre of the knot on the belly, running down to the 4 plugs. I filed and sanded it to show it up clearly. I wish I had made the plugs out of some darker Yew, but I didn't have anything suitable.
It's a matter of going slow and steady removing wood cautiously to maintain a smooth bend to the bow. I need to open the garage door to get decent daylight onto the tiller for a good picture, I'll do that tomorrow by which time it should be coming back enough to see the curve.
I've just added the pic of the bow at 60# (taken first thing Saturday morning before I've done any more work)