Have you tried using the F word? That usually helps.
I always have a hard time using two/three way pullers in a confined space when I'm upside down, cranky and cursing a blue streak.
If I were trying to get that off, I'd whip up a bolt-on puller out of angle iron and a big-a$$ bolt & nut. Bolt the angle iron to the flange, with the big-a$$ bolt passing through and pressing against the shaft. Hold the nut with a wrench, tighten the bolt. Even easier if you weld the nut to the angle iron.
I've made these to open VW 020 tranny cases, pull axles etc.. Here's an example:
