Originally Posted By PDR Dude
Had a 340 rebuilt about a year ago. The machine shop was very adamant about using Brad Penn break in oil for the first 500 miles. Keep your foot out of it and vary the RPMs as much as possible.

It really sounds like your machine shop is really old school on clearances and parts work
You really need to load the rings as soon as possible to help seat them, DO NOT baby the motor for that long tsk twocents

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)