Definitely use a no-bypass filter for break-in - and for continued use as well! A bypass filter is bypassing oil a large percentage of the time under normal use! It depends on rpm and oil viscosity. In the past for race or high performance applications, we either modified the block to run chevy no-bypass filters, or used remote filter mounts with no-bypass filters.
We wiped 13 lobes on a new solid lifter cam in the 428 FE we were freshing up for testing our new Shaft Girdle system (and for eventual installation in John's 63 1/2 Galaxie 500XL). The failure was due to an oversight on our part regarding an incompatible pushrod/adjuster combo. What was worse, however, was the wiped rod, main, and cam bearings, and the pieces of stuff embedded in the piston skirts!
We knew better, but had gone ahead and stuck it on the dyno with a stock type bypass filter.....
As we sat down to design a "no-bypass" adapter that we could machine and sell, the light bulb went off - why not make a full-flow, non-bypass filter for Fords???
We designed it and in the process tested and compared it with a dozen or so bypass type filters currently available. We have a heavy 600psi burst strength can, 440 sq. in. filter media (more than any of the ones we cut apart, substantially more than most), and a standpipe and anti-drainback valve. In our testing, the pressure drop at 8gpm flow for the bypass-type filters ranged from 8psi to 24 psi - our non-bypass filter has a pressure drop of only 8psi at 8gpm!
I don't mean to make this a commercial, and certainly do not want to violate the intent of this forum, but we're excited about having a really premium filter available - and kind of surprised that more people haven't asked this question!
IDT, B F Evans, Panhandle Performance, Jon Kaase, Keith Craft, Steve Peterson Performance Fords, and other dealers are already selling our Jomar Pro-Filter. You can see more at www.jomarperformance.com.
ps. Crower recommended (after we wiped the first cam) that we use Rotella T Heavy Duty SAE 15W-40 oil for cam break-in. Evidently there is little or no zinc additive in most current automotive oil, and enough more in this oil to help protect the lobes during the initial break-in process.