Just replace the numbers in the below schematic for an 80 to 60mm adapter with 120 to 92:
http://www.voidyourwarranty.net/revi...ts/index2.php3
Get a thin piece of aluminum flashing at Home Depot and for a pro look pick up a pop rivet gun and rivets. You can cut the flashing with scissors and use a desk corner to make the bends. Rivet it together and you have a pro looking adapter. Here's one I made for my Chevette core in about a half hour:
http://www.procooling.com/~phaestus/chevettecore.jpg