If I may offer another suggestion...how about running a different fluid through there?

I can't remember if these cars already have a power steering fluid cooler or an engine oil cooler, but I imagine that it wouldn't be difficult to make the old tranny oil cooler serve that purpose.

Another thought, if feasible, would be to keep it a tranny oil cooler...for the manual. I know that some manual trannies (the ZF 6 speed that Ford uses in their trucks, for example) get warm enough that a cooler's actually necessary. I'm sure that this tranny won't routinely get that warm, but every little bit helps.

Just a thought...good luck!