here are a few pictures of a aftermarket BMW boxer engine oilpan/cooler. I,ve always found these to look slick, they might even work too. pretty simple and straight forward looking to make; a hollowed out block of aluminum. Machine it to take three aluminum tubes and TIG them into place. Leave room between the tubes to fit the sump pickup. You'll need to make an extension for the sump as well; it'll be the same depth as the cooler will be. Extras pan gaskets plus two sump gaskets and longer sump bolts are needed.
When putting this one on I found it to be a bit of three hands operation. you can use two or three bolts to hold the cooler up as the sump and sump extension is fitted then when the sump is where and how it should be, remove the extra bolts; add the bottom pan gasket (you did add the upper gasket first?) and finally the oil pan.
Gotta make one of these for the hotrod project.