Yes, the timing does affect the temp.

Yes, I firmly believe the shroud helps that much. The reason the pusher
helped your situation is that you are compensating for two other problems.
First the fan. When you say "flex fan" I picture one of those flimsy,
aluminum blade (shaped something like an elongated tear drop) fans that were
popular 20 years ago. They're junk!! 17" sounds like a good size, notice
that the factory fans are more of a "square" or rectangle shape, and have
some flexibility. These are much more effective. Second, your fan is too
far back to be effective. It should be about 3/4" to 1" back from the core,
not 3". For the shroud to work with the fan effectively, the fan pitch
should be 1/2 to 2/3 into the shround. If the shroud you are getting from
Griffin doesn't have it, you might want to make provision for high speed
cooling. You might have seen on OEM shrouds where there are "windows" cut
in the shroud with rubber flaps over them. At idle the pulling motion of
the fan keeps these flaps closed allowing the fan to pull air through the
full core. At high speed (freeway say) there is enough ram effect from the
air coming through the grille that it "blows" the flaps open to allow more
flow through the shroud.

Whether or not you have other problems is hard to say from here. But with
all the stuff you've described so far I would suggest fixing those issues
and seeing where you sit then before trying more diagnosis. Process of
elimination of the most obvious you know.