If your truck is a Carbureted 85' then you can adapt the equipment (if feasible) and they wont know any difference.
In my MR2, I have an engine from an early 4A style engine, specifically from 1983.5-1986.5 whereas my car is a 1987. How are they different you ask? Glad you asked, the engine block has ribs on the side that are a dead give away. 3 Rib blocks are the early style and in 1987 they switched to stronger 7 rib blocks that also had stronger internals and wider main & rod bearings.
So TECHNICALLY, I had a smog-illegal engine. Right, its an engine thats earlier than the car. Big no-no. But of course I wasnt worried. Do I think the smog tech knows
about that engine? Helllssss-no.
Just smog it. Then rip the crap gas & power robbing smog equipment off. That's what I did.