he hat switch is my biggest concern, as I'm not sure if I'll be able to exploit the 8 button potential but 4 buttons isnt that bad either.
I rewire, for friend, a old CH PRO Throttle gameport, using the USB circuit of a nameless stick:

His USB circuit provide 4 axis, one HAT (8 angle/corner) and 12 buttons.
The CH PRO Throttle gameport originaly have 20 buttons, distribute in four 4 way HATS plus more 4
push buttons.
CH PRO Throttle whit new USB circuit:

To allow all original 20 buttons and HATs of CH PRO Throttle to continue working, I used the corners of HAT (of USB stick) as 4 buttons, using diodes to avoid that two buttons pressed at the same time in diagonal generated commands. This provide me the necessary 20 buttons.
Diodes in one HAT, wiring in original Stick 8 way HAT. This allow to use HAT corners as four buttons:

Tip - avoid solder in USB circuit, or use grounded iron. They are sensitive to ESD.
Others gameport sticks awaiting rewire is:
One Suncom Hawk, one CH F16 Combatstik, one CH Force FX (maybee whit Logitec FF circuit) and one
TM TopGun. I like this stics due to his design based on real ones.
Sokol1