273 Radiator for 340?

Thanks to all for the comments suggestions so far. I just got done dropping it off at the radiator shop. The shop owner told me his idea and showed me the materials that would be used and some techniques that would be applied. His idea is using two 3/4 inch rows of tubing. This should help with the fan spacing. He showed me the internals of the tubing, grids (small squares) that run in one direction with the next running the opposite direction. I guess this is to agitate the liquid as it flows down the tubing. In addition to that he mentioned they would do a "dimple" process, not sure on that will have to ask again about it. He also talked about fin count and could possibly be reducing that count if necessary to have more flow though.
Yes I will be using a cast iron pump, correct year timing cover etc. to match my block (even though the duster is a 71). I do live in the NW and on an island in the Puget Sound so the weather is pretty mild but I want to be able to drive it over the pass, into the dessert etc. on occasion.