Something to consider, I just replaced a flan blade similar to yours with a Vintage Air, direct mount,
https://vintageair.com/direct-mount-fan-blade-17-25-in-x-2-in-steel-fan/ . I went from 18 flex fan to 17 steel blade, the Vintage Air fan moves twice the air the flex fan did. I was having issues with heat at idle with A/C on. The new fan cured it so well I can now replace the 180 thermostat with a 195 to help with heat in the winter. I made a new shroud to fit the smaller diameter fan.
My fan is about 3/4" from the core, the flex fan was at the same distance. Build a shroud with a removeable section for alternator/belt maintenance.
