The bandsaw blade left wider spaces between the keys and reduced the amount of fitting I had to do, and I was able to remove the saw marks with a coarse mill file. I made the angled undercuts on the naturals with a small backsaw and removed the waste and relieved under their covered parts with a chisel so that they're about 4mm wider at the front and on top than on the bottom.
I had to deepen the wide part of the balance pin holes a little, and some of the wood had sprung a little to one side, and because they were used ones most of the key pins had been bent so the spacing was uneven at the front and at the back. I was able to fix this mostly by twisting and bending the pins as prescribed
by Hansing, using pliers with protective wooden sleeves so I wouldn't nick them, and only had to plane a couple of keys that looked kind of too close together.
The ivories often are rounded with a file on the sides neighboring other ivories, and the heads chamfered at the back edge in front of the sharps. This makes them look funny when someone reglues them on the wrong keys.