With my limited knowledge on Wilwood (but have good basic brake knowledge) I throw out some thoughts:
1. Did you bleed the new master cylinder per the instruction before you connected it?
2. Are all the connections tight?
3. Are the bleed nipples closed?
4. If pedal has too much travel and can’t pump it up and you did steps 1 to3 above, my guess is you have a bad master cylinder.
5. Did you start bleeding at the brake furthest away from the master cylinder?
6. Did you bleed until the new fluid and all air bubbles were gone?
7. Sometimes, a different color brake fluid will really help. This is what I do… I alternate between clear and blue the no errors on brake fluid change out every two years.
Mark
427 S/C, Flame Yellow, B2 Motorsports 427ci Stroker Dart SBF, TKO600, 3.73 Posi, Avon tires and so much more.