Have you tried using a Gano filter?
I installed one in my 65( all stock) a few years ago after having my rad cleaned out , new hoses ect. But have never used the factory shroud.After the initial install I ran her and checked the trap after about an hour of driving or so. I then checked it once every other week for a month or so and got loads of fust out of my system.
Even on the hottest of days she never runs hot.
here is a
LINK to a page with loads of info on them you can even make your own.
I hope this helps
Cheers!