Since you are disconnected from the engine pulley.....no metal to metal heat transfer to damage your front crank seal, I'd put a sheet metal "heat" shield between the sprocket and the engine pulley and take a cutting torch and cut the shaft....if you don't intend on keeping it.
If you do, rig a slam hammer type thing on the end of the shaft and apply heat to the yoke to red, not the shaft.
To make a slide hammer hootus, weld a 1" dia. bolt...maybe 12" long with a piece of 2x2xhalf inch or so, steel plate slid over and welded to it prior to welding the bolt to the splined shaft. Get a 3-4# sledge and when you get the yoke sizzling hot smack it, rotate 180 smack, etc. etc. while keeping the heat on the yoke.
