340 break in question

I've had it happen a few times before, trying to get it to run and get initial timing set whilst keeping it running....long story short, you're fine, just get it up to 2k and do your cam break in for 20 min, varying from 2k-3k slowly for the time. Then shut it down an check things over (valves, leaks, etc). If all is well, drive it up to 3500 in 2nd gear and let off a few times letting it pull against the motor to slow you (making sure the rings are seated), then dive it like you are going to drive it ....aka, hammer down.