Check the "radiator" thread in this forum (it's older than 45 days so change the date range). I'm very happy with my custom radiator/oil cooler from alumrad (he makes the custom units for Howe). Paid $600 but it solved my oil temp problem without adding a second air/oil cooler.
If you call Bryan, mention my name as he has the drawing for the radiator filed by name.
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Marty Doane
ITS RX7 #13
CenDiv WMR