Pegson Marlow Impeller removal

Have now removed the impeller nut (was RH thread, see previous post), Used copious amounts of penetrating fluid and a judicious application of heat.

I now need to remove the impeller itself. It appears to be keyed onto a tapered shaft (crankshaft) and has two threaded holes either side of the shaft. However, the threads appear degraded (50+ years pumping water) and I am uncertain what thread they are or what size.
Would it be easier to use a 3 legged puller on the static part of the impeller assy ? After all, its all got to come off somehow and by pulling the housing off it will take the impeller with it.
Wish I had a manual, would make life an awful lot easier !

If it is a tapered shaft put the nut back on and support the impeller a swift sharp blow to the shaft end and it will come loose.

I know Jabsco make an impeller removal tool, we have a couple in work for the jabsco pumps on the boats we build/ refit. Its basically like a puller except it clamps to the side of the impeller so it doesnt cause damage to the blades.