124 has a belt, which is now probably every bit as good as a chain.
But in the old days Fiat belts were as reliable as a rubber band and not much stronger. I helped my buddy replace heads in a 69 124 and his sister's 128sl. They broke and every valve was bent, and the guides were suspect too.
Article has errors. No MX5s are forced induction. And as observed, trim levels were not identified.
I had the same experience with my 1976 Fiat. Belt went and so did all the valves. I had it repaired at great expense and then NHTSA condemned the car for structural rust and Fiat had to pay me Blue Book value for the car. Then I went out and bought another one.