1986 318, roller or hydro

If I'm not mistaken, early roller cam engines still used the V belt system. I could be wrong.
Early roller cam engines did indeed also come with the standard from end. So this is what I base my thought and choice on. That is if I'm correct.

67dart273 has the simplest and accurate way to answer the question.
Take out a pushrods and measure it. A ruler or tape measure would do. Since the length difference is a good bit.