[dsraven]

-a flat piece of 1/8 sheet cut to fit the carb pattern.
-a piece of 16ga sheet metal bent to fit the rounded corners of the carb profile, then welded at the seam where they lap to form a rectangular tube that fits the carb pattern, this will fit onto the 1/8 sheet above
-another piece of 16ga sheet cut to fit the diameter of your donor air filter, whether that be a round donut shape or whatever
-weld all this stuff together to form the spacer under the new/donor air filter housing. use some epoxy or jb weld to ensure the welds are sealed

for a cold air intake skip the round adapter on the top and simply ensure the chimney protruding upwards is the right diameter to accept some of those silicone rubber cold air intake parts you can buy online. use abs drain pipe to connect the dots between the carb adapter and the conical air filter mounted where you choose