Truck engines are almost always removed as a separate unit - it is so much easier. Are your mounts free? The transmission to engine mount braces released?
An SBC is bolted to the transmission bell housing with just 6 bolts. If they are out and the 3 T/C to flexplate bolts are out - it should come apart.
The trick is to raise the engine and transmission together - at first. When the top of the tranny hits the cab, brace it in place with a jack under the oil pan or a 4 X 4 stuffed between the tail and the body/frame.
Now with both units up higher than the motor mounts, grab the front of the motor and yank it hard towards the front. If they are stubborn, use a bar to separate them. They have to come apart.
If and when the locating pins on the back of the motor clear their bores in the bellhousing, the engine will swing towards the front and (depending how you have it hung) it may tilt either up or down.
Look at this procedure again. If you still feel that you need to pull the radiator support, bump this and I will describe the process. But let me tell you, it is way more involved than lifting an engine from a GM pickup truck.