455fbird,

Good point on that blocking, but the big electric fan (or the two smaller ones if you had that config) should normally "free-flow" and spin to some extent when not energized. If they don't then yes, they could inhibit the flow. You know, there have been several posts here over the years that alluded to higher temps when traveling at cruise speed. Never could figure that out, but your point may be a part of it if the fan blades are just sitting there blocking flow.
Most of you know all the different tests I did a year or so back to fix my high temp issues. For my 68 400 it took a large front electric fan pushing and a large new flex-fan inside pulling!! That combo ended my over-heat concerns for good.
CAVEAT: I went through several diffent temp gages during that testing period, and ALL showed different temp readings! So you just never know if that gage is being honest.