The other question is how to get the water up to a front radiator.
The options I see are
(1) use 1.25” or 1.5” aluminum hard line all the way, and use a tubing bender. Then braze the sections together. This requires buying a tubing bender.
(2) Corrugated Stainless Steel Tubing. This is semi flexible tubing that can easily be bent to fit the car. Stainless is not as thermally conductive as aluminum, but the larger surface area should provide a great deal of addition cooling capacity. Also, because of the rough internal surface, there is a LOT of turbulence which forces more of the water in contact with the surface. Corrugated stainless can also be TIG brazed.
Another option is to use multiple smaller tubes under the car. This increases ground clearance, you don’t have big lumps hanging down, and greatly increases surface area so you can run a much smaller radiator. Multiple smaller tubes are also much less visible from outside the car.
I think routing the radiator tubes in the heater ducts is a bad idea because the radiator tube will rub on the heater ducts, and will eventually rub through. Also, you don’t get any additional cooling as the heater ducts are well insulated.
http://www.flexicraft.com/Industrial_Hose/SU1/
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