broken bolts try using some screw extractors. I had some broken ex. manifold bolt on my 455 and that worked on e few of them. For the rest, I took a chivel and a hammer and backed them out. You will need lots of patience for that. You could also try heating them up and melting some candle wax into the threads, that works pretty good too. good lick.
sears has some tools that may help. they have a set of what look like sockets that are for rounded/rusted bolts. they are in two sets of 5. when you look in the "business" end of these sockets, they are six points that curve towards the center. it is designed to grip into the bolt. if you go to a sears tool center/ sears store you will be able to fins them. they fit onto a 3/8 size ratchet. they may help. they also have a nut splitter. you can split the nut that is frozen/rusted (such as the bolt holding the exhaust pipe to the exhaust manifold). also if there are any stubbon nuts/ bolts, find a good machine shop to remove them. it is worth the money not to have ruined parts. you do not want to ruin a head, intake, or timing chain cover to try and save a buck. TRUST ME!!! john