Hi Tony
I do still use this gauge, but reserve it mostly for curved work.
If I built it over I would make two changes. the first one is the blade. You can use a spade bit, especially one that is HSS - no need to worry about heat treating or loss of temper when grinding. However, there is a simpler method - use a HSS drill bit (as I have in this panel gauge) ...
The other change would be to add mortice in which the beam can run instead of the tenon I used. The tenon works, but the mortice would be better.
Regards from Perth
Derek