I've got roughly 350 miles on the engine i just finished building. Here's how I've broken it in thus far:

Put straight 30W NON-DETERGENT oil in the engine. Run the engine for 30-40 minutes with the car still up on jacks. Shut it off, change the oil and filter.

Put straight 30W NON-DETERGENT oil in the engine. Drive the car for 100 miles. Like someone said earlier, you don't want to cruise. Vary the RPM, don't rocket up and down the tach. Just let the engine slowly accelerate and decelerate. Don't take the RPM past 4k. Change the oil and filter.

Put normal 10W30 oil in the engine. NO SYNTHETICS. Use standard basic motor oil. Drive for 300-500 miles like you did before. Don't rev past 4,500 and vary the RPM as much as possible. Again, don't shoot the engine through its revs. Let it run up and down slowly. Change the oil and filter.

I'm on that last step now. I'm going to change the oil when I have 400 miles on the engine. During the next 500 miles I'm gonna start taking the revs up to around 5,500, but still varying the RPM and no race driving yet. I'm not gonna redline her until I get 1,000 miles on the engine. I'm probably being overly cautious, but I'd much rather be too careful than too careless. I'd burst into tears if I blew her up after putting this mucn money and effort in.