Couple questions

I have a 1989 GMC white wia, buddy of mine turned my engine up the other day, is it true that it is done by adjusting the rails?
Also, everyone tells me my engine is a big cam, but the plate says n14 from 89, we’re parts interchangeable?

 

It all depends what was ‘turned up’.
Was the hp increased?
Was the max rpm increased?

 

With the older engines, when it was turned up. Fuel was increased to it.