[GySgtFrank]

A large oil cooler of some sort in that line would be a good idea, as you currently only have part of the required cooling system. Especially as you're going to be running this at low speeds where air flow through that small radiator is going to be less than ideal. At 2000 -3000 rpm you won't even be into the power band for a rotary. Of course considering what you've shoehorned it into, the lower power output down low might be a good thing. If you ever push it above 3000, where the rotary really takes off, that thing is going to be terrifying instead of just scary/borderline insane.

edit: if you need it I have a stock (radiator style) cooler from the 12A that was in my 79. There were two types used in the RXs. A radiator style in the early (79-80) models and the beehive style under the oil filter on the 81-85 models. 86 and up went back to the radiator style up front as they proved to be superior to the beehive style cooler.