If you are fitting new p/b what is your link height and the condition of the bolt holes? In my experience parts and labor to re-pin and bush on these small track groups can exceed the cost of brand new link assemblies.
Like most old style final drives the sprocket rim is press fitted to the sprocket shaft. The sprocket needs to be pulled off the shaft (loosen the nut about 1/4" only).Make sure you press on the shaft and pull on the sprocket. Don't push on the back as you could damage the final drive.
The sprocket is pressed on to between 10 to 20 tons but you may need a 50 ton cylinder or larger to pull it off.
When a suitable puller is rigged up, pressing on the shaft and pulling on the rim, ensuring the nut is loose so that it can't fly off give the rim a sharp thwack with a big hammer and a lump of wood and it should come off.
You will also need to press it back on and probably replace the sprocket seal