Replacement distributor

Spark plugs are specific to the engine. It does not matter what generates the spark voltage.

1984 was the first year for GM's High Energy Ignition, (HEI) system. The camshaft gear stayed the same so the distributor was a drop-in replacement, but there is a dropping resistor in your truck's wiring that is needed with breaker points but not with the HEI distributor. That resistor could be a white ceramic ballast resistor, about 2 1/2 inches long and 3/4" square, or it could be a resistance wire that is part of the wiring harness. That has to be removed.

1986 was a changeover year where both the old-style and new-style distributors were used. For your application, you need the older style with a vacuum advance unit hanging off the side.