[Coley]

First, welcome to the website...always good to have new people come aboard in the hobby.
Second, the engine(s) available in these trucks after 1963 (I think) was a new series of engine and very different than the earlier 'stovebolt' engines which, to my recollection, were actually 235 ci engines....while the 'new' series came in at least 4 sizes: 194 ci (cars only?), 230 ci, 250 ci and 292 ci.
Now google the GM 235 stovebolt engine vs. the 230 ci 1965 GM 6 cylinder engines and this will be a little clearer.
Regardless, these (newer) 230 ci engines aren't too hard to find and you might even find the 250 ci or even the 292 ci 6 cylinders while you are at it.

check it out and again...welcome!

All Good
Coley