So you are mainly driving the 1964 Chevy truck on the street and taking it to car shows. One question related to car shows is how "stock" do you want the truck?
I am more familiar with the 250 than the 230. My Chilton's manual shows a slightly lower lift for the stock 230 cam than the stock 250 cam. Never seen this mentioned before.
All stock? Use the original cam, for the 250 it is GM 3864819. Best bottom end power at 500 rpm. Best application for a farm truck in fields and woods. With this cam, the truck will carry a full load in the bed, and motivate without bucking at idle speed. You may want to consider replacing the fiber camshaft gear with metal gears (non-GM), your choice here.
All GM? Use the original cam, GM 3864819 or the GM Marine cam, GM 3891590. The Marine cam is used in inboard marine engines. Good low and mid rpm cam, slightly more overall power. Stock OEM valve springs are fine.
Better street power and drive-ability? For power to 4000 or 4500 rpm, the Comp Cams C60-240H-8, Crower 248HDP, or Isky 231-M Mile-A-Mor. Still plenty of low end power. On the street with the stock cam, you run out of revs fairly quick. And on the street you don't need that stout bottom end power as much. These are still mild cams, milder than recommended for most real performance applications. For reference only, a popular street performance cam is a Comp Cams C60-260H-10.
One of the biggest power gains is enlarging the valves to 1.84" intake and 1.6" exhaust (hardened exhaust seats). Stock is 1.7" and 1.5" respectively. For higher rpm applications 1.94" intake valves can be used.
