My other thread, https://theamcforum.com/forum/ruined-my-radiator-and-fan-today_topic118405.html , where I documented my woes of an original flex fan on a March serpentine system that ate up my radiator, has lead me to this thread where I'm finally going to use the Contour unit I obtained from a junk yard several year ago.  First thing, and its been stated here before, is the Contour shroud fits perfectly in the radiator, both the original radiator and the replacement Champion #407:

even with a rubber channel installed over the edge to protect the core:  https://www.steelerubber.com/search?q=70-3167-33  Not shown, to secure it to the radiator I drilled through each plastic tab (4 plcs), through the radiator mounting bracket, and used sheet metal screws.  I ground off the screws that stuck through the radiator bracket so they were flush with the mounting side.

My next opportunity (that's what they called "problems" at work) is how to control the fans.  Now I know there have been many ways to wire and control the fans presented in this thread, but I spent an entire day searching different brands, watching installation videos (mostly Mustangs) and reading installation instructions of PWM (pulse width modulator) controllers and pulled the trigger on a Derale # 16797 from Summit (you have to buy from certain vendors to be eligible for their warranty).  I will admit I was biased by a previous Derale dual fan and shroud purchase with a PWM that I couldn't get to fit, but it offers what I think I need in a nice size and should be easy to wire (I have also already done the wiring from the battery to the PWM, so I'm halfway there).  PWM is to be delivered in a few days, so I'll be back.