I believe in the 20 min.@2000RPM method is the way to go,I have rebuilt many engines including changing only cam and lifters and I have never had a problem with them coming back.And besides if you think about it the whole idea of the "500 mile break-in" is BS,I know alot of you have seen this done before on shows on Speed Channel and I have seen it at engine shops,they take a freshly built engine and run the heck out them on the dyno,that`s their"500 mile break-in",and the engines usually last without problems.