I would use three things, Kroil, daily soaking for a week, the blue wrench but have to keep the heat medium as to not melt the aluminum, and as mentioned a puller, which could be shop-made.
What I've done before (had a bandsaw wheel very similar up to a point, frozen on a gearbox output shaft) is start with a 2pc shaft collar that will fit behind the hub (mcMaster carr or others). Then weld ears to each side of the collar so you can get out far enough to have tension rods go thru 2 of the 4 holes in the fan. The "ears" may need a rib behind them for structure. Last part is a heavy tube or channel with 3 holes, 2 for the tension rods and a tapped one or weld-nut in the center. A pressure screw with a hardened tip is best but a gr8 bolt turned to a point on the lathe will suffice. Fine threads can help. Grease or anti-seize the center bolt and the contact point. So you assemble the puller, apply light pressure, warm the hub a little bit and slowly increase pressure. If the puller starts bending and lots of torque on the center bolt its time to stop and re-evaluate. If slow movement is detected then you are doing great, just keep going. Best of luck with the restoration!
