Doug,
You built nice tools, both of them. Thanks for sharing.
I also have the very same problem with original milling vise handle and I am using 19 mm (3/4") combination spanner for that purpose. It's 6" machine vise, little bit big for this mill, but this size is very useful sometimes. Even I have three 19mm spanners, I am always using the same spanner for drawbar. As I can see from your posts we have the same mill/drill (HF40939 mini knee mill) but the only difference is that my riser block is 5" high and I think your one is about 3 1/2 - 4" high. I am also thinking about making speed handle, but it will take me some more time as my idea is to do it on the lathe in the same way as cutting keyways.
Best regards
LMMasterMariner