Griffin radiator
That's a good question. I'm not a thermodynamics expert, so I would call Griffin and see what they say. 21 x 17 core with two 1.25" rows. I don't know. Maybe. Ask them how many cooling fins per inch. You want a high efficiency core. That's 14 - 16 cooling fins per inch. If that Griffin won't do it, call US Radiator. Every one of their radiators is custom made and they will make a brass/copper that will cool the space shuttle.