Jon,
You will get alot of opinions on engine break in, but here is what has worked for me.
I have a rebuilt GMC 228 engine. During the first 50 miles or so I ran the engine around town, up and down hills ect. I worked the engine through all the gears and make sure your oil pressure stays up. Then I changed the oil. The next couple of runs I repeated the same driving and then added some straight high way runs. After about 250 miles I changed the oil again. Other than that, I tried not to rev the engine to hard, or "lug" engine.
Now that the engine has 1300 miles on it anything is fair game and It runs super smooth at any speed.
Don't forget to stay on top of your valve adjustments. Also the timing might need some re-checking after the first 1000 miles or so.
Good luck and keep us posted.
