Try the Ms. Pac-Man/Galaga replacement. It's basically a super with a ball-top stick, but the restrictor is a diamond shape, not round. Also, the stick is shorter, so you may need to mount it from the top unless you have a metal panel.
Also check out the 4-8way switchable sticks from
Ultimarc. They have diamond restrictors, and you can always leave it switched to 4-way full time.