Help needed passing Emissions!

In areas of Oregon, its 1975 and up. Failing is free and you can go through as many times as you want you just can't tune in their bay. I'd run my 76 F-150 4x4 home with a mild 460 (which they never came with) and decrease the timing and kick the idle up then go pass come home and reset it all to where I had it. I probably dove that truck 50 miles a year so I wasn't exactly killing the earth on my own.