Just about any oil cooler will work. Like Rick said, since you will be running lines for the cooler go ahead and install a remote filter mount (or better yet, dual). You can find coolers of just about any size and shape as well as remote filter setups on Ebay pretty cheaply.
I just got a heavy duty oil cooler, lines and adapter directly from the Flex-a-lite factory for less than half price. Got the dual filter mount with hose fittings for about $15 on Ebay. So, for under $125, I get thermostatically regulated and VERY clean oil. Plus, more of it (better still).
Dan