n2 block, greddy oil filter block, and setrab cooler is what I'm planning to do. putting the cooler in the grill area is a nice design. ARC uses it, but their coolers are efficient.
here is a pic of the $1000 ARC oil cooler for s13 silvia. its nice but i think ARC discontinued it.
i've also seen people put it on the driver or passenger side of the bumper. RX7 FDs are set up like that stock from the factory with dual oil coolers.