After putting a new 5.7L engine in a 96 Chevy pickup I had a hard time getting the air out of the block. At least that's what appeared to be the problem. I filled the radiator with two gallons of antifreeze and one gallon of water and fired her up. The water coolant went down maybe a quart so I topped it off. I ran the engine for about 5 minutes waiting for the thermostat to open, meanwhile the temp gage hit about 260 degrees. I shut it down and waited a bit. The radiator gargled and I was able to put about another quart of coolant, started back up for a few minutes and temp was at 260 again. this process went on for about a half hour before it finally purged and the temp went down to 190 degrees.
Is there a better way? Should I fill the block with coolant first?

-Kevin