I had mine recored at he local radiator shop. He offered 2 options, use an original style 3 pass core, or for 50$ more(totla 200 Canadian) use an industrial(used in fixed industral equipmqnt) 4 pass aluminum core, much like the 740 rads. It has raised the capacity by about 1/2 litre and when painted black looks original. The rad shop said with a good fan it was capable of cooling a mild small-block chev(he does most of the dirt track cars around here, he is reliable).
While you are at the rad shop have them move the overflow tube to the other side and install a catch can(use an apropriate rad cap for the job), and have a drain installed in the lower tank, a good improvement.

Merci

Yvan
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65 122s/73 1800es/80 262c(350ci v8)/89 745t/87 780/89 740/89 740t/ 86 745 and too many parts cars and projects to list