Hi BB,
there is no such thing as a simple engine swap with any Briggs motor (another reason I hate them) every time the blade carrier is different or the boss is different and that always cost about 2 hours just getting this simple thing fixed. Honda and Chonda bosses usually come off ok but sometimes the Briggs are a real pain. On dead Briggs I just cut the shaft with the boss still on it and throw it in my box of bosses so the if I need it later I can just put it in the press and push it out. As in your case I use a bearing puller I have had for years and it gets behind the boss and snug up against the shaft and then you can pull the boss off. Problem with the 3 jaw pullers is they are pulling from out too wide, you need to be in snug near the shaft. You can certainly make up a puller but it would take a few hours
