I tried several types but I probably gave up to early. It looks as though there's a small step down between the bushing diameter and the crank end diameter. So if I use a drift that will fit into the crank end the grease just pushes past the bushing, and if I use a drift that is snug in the bushing it bottoms out when it hits the crank lip diameter.
fill the bushing right to the 'front' with grease, get your drift that's snug in it and whack it hard with a decent hammer. it'll take a few goes refilling with grease and repeating but it will come out.
neil.