The Hot Rod article is about a 261 engine:
Soupin' Up a 261 Engine, SOUP THAT CHEV (1954/55 261 truck engine)It is a nice read, but I doubt that it can advise you on your 235 ("what to buy/do on my '56 truck with a 235 engine")?
Your 1956 235 most likely has the 261 cam in it, and your 235 most likely has a higher compression head than on an original 261.
My ignorant guess is that the best ways to "get more out of you 235" would be bigger displacement (bored cylinders) and careful, judicious, increase in carburetion.
The carburetion issue/options/opinions will give you headaches.
What is the engine serial number on your 1956 235?
