Water Pump trouble

I have a 1987 F-150 with a 302 motor and my water pump has recently gone bad. We got the new one and went to replace it. We took 4 of the 6 bolts holding the water pump out. The last 2 bolts have frozen into the block and the heads of the bolts broke off. We tried using an ez-out tool but that broke also. The water pump should normally just slide over the bolts while they are still in the block but something is still holding it on and we dont know what. Does anyone have any suggestions on how to get this thing off?

Welcome to the forum. This link has a photo of the pump gasket. It shows the location of 7 fasteners.
http://www.partsamerica.com/ProductDetail.aspx?mfrcode=FEL&mfrpartnumber=35397&parttype=110&ptset=A

drill them out

okay drill them out okay BUT BE CAREFULL I had the same problem on my 87 f-150 5.0 with efi. the next to alst bolt broke off i ended up drilling it out and well my drill bit bent and drilled into the timing cover. when you are drilling use something like wd-40 or pb blaster and spray the bit when drilling to keep it cool and don't drill sideways lol

oh yeah the pump should slide right off depending on how long it been on there tap it with an hammer and it should break loose