NO AIR TOOLS! If they are the slightest bit frozen, you will break them off for sure. I'm not 100% sure about the 4.9 liter. But I know for a fact the 5.0 V-8 is famous for having a couple of long 4" bolts that go through the timing cover, that can and will break very easily. Use a lot of care when trying to remove them. Once you break them loose, work them back and forth BY HAND, little by little until you get them out.
Then wire brush all of the threads, and liberally apply a good grade of anti seize to the full length of the threads before you reinstall them. I've replaced my water pump twice. (Once because it was leaking, and again because I had a small coolant leak by the timing cover). So rather than reinstall an old pump, I purchased a new one instead. It wasn't that much money for a new OEM water pump, so it made no sense to put the old one back in.
Again, I'm not sure if the 4.9 is set up the same way. But if it is you'll want to be extra careful. Go slow, take your time, and don't force anything.