I put a new (to me) crank, bearings, cam, lifters, rings in my 270 with a full flow oil filter conversion. I am running a K&N 2 stage filter and I used a high ZDDP content break-in oil from Brad Penn (8 quarts) . . . how many miles should I run this oil before the first oil change? I have run the 2000 rpm / 20 minute cam break in and some gentle driving for 50 miles and a few mildly aggressive accelerations in the last 30 miles . . . Getting close to 120 miles and thinking I should dump the oil.

http://www.amref.com/CMSFiles/File/bp_pb/7120_BP_PENN-GRADE_1_Break-In_Oil_PB.pdf

Well, after some thought on options, I decided to dump the oil as the next drive I am going on will be about a 500 mile round trip and that seemed to be a little much for the oil that first sloshed around in a fresh rebuild and 20 minute cam run-in.

I put in 8 quarts of Delo 400, I'll change that when I get back from my road trip and then get on the 3000 mile plan.

I tend to put 50 miles on the fresh build and then change the filter only and top off the oil. Then I drain and replace both at 500 miles.

Too late for you now, but for 25 years I've dumped the oil and changed the filter always right after the first run (Cam break-in). Then again after the first day of test driving and tuning, which may mean a couple of hours total run time, or 20-40 miles. Then AGAIN at 500 miles, and AGAIN at 1000-1500, and then fall on your regular schedule. Filter every time too up until that point.
The first run is with regular mineral oil, nothing special, no extra additives, and especially no friction modifying stuff. Good ZDDP oil is ok. All the other commercial additives in a can are a no-no.

I haven't lost a cam lobe yet on my builds... too many builds to count

MINERAL OIL,NEVER HERD OF THAT IN A ENGINE BEFORE...

a.k.a. Dinosaur oil for us dinosaurs, non-synthetic