Coolant Additive

No modifications at all. And there's no need to use Evans' flush fluid, either. You totally drain the cooling system, flush it out with clean water and drain it again, blow out as much water as you can if you have access to shop air or just leave the system open to drip dry as long as you can, then put in the Evans coolant. Loosen the radiator cap after the first dozen trips or so to vent off the steam that results from residual water, until there stops being residual steam pressure, then forget the cooling system exists.

I ran a higher-temp thermostat in the (fuel-injected) truck to wring more MPGs, cleaner exhaust, and better driveability out of it, with the overboil protection assured by the Evans coolant -- and that strategy worked -- but I generally run 180° thermostats in my carbureted cars, Evans coolant or no Evans coolant, because higher temp thermostat = higher underhood temp = bitchy hot start/hot idle issues because of the open, low-pressure fuel system involved with a carburetor.