This should help.
How To Properly Wire Electric Cooling Fans
I did mine a little different since I use Derale fan controller. I toggle the grounds through the relays rather than the 12+.
This is the fan controller I use...
Middle part of this page has a filter by on the left. But I don't see 1.5"
Green Stripe® Vulco-Flex® Coolant Hose | Coolant Hose | Engine Hose | Fluid Power | Gates Corporation
This one isn't specifically flex hose and you maybe able to use couplers to accomplish your task. 1.5 is listed...
If you can live with a GM part...
64-77 Chevelle El Camino Vacuum Canister
Might could work too;
Classic Industries | Restoration Parts | Mopar Parts | Camaro Parts | Firebird Parts | Nova Parts | Impala Parts | GM Truck Parts | Tri-Five Chevy Parts
When I was working through my issue I hit different parts of the radiator, water neck, heads, and water passages for temp. Water neck was always warmest. An IR thermometer gives you a very good idea where it's hot.