If you intend to switch to electronic ignition, there are better and cheaper ways to do it with off the shelf GM parts rather than with a Pertonix unit.
The BB is normally 5 deg BTDC.
What makes you think your dizzy/timing is responsible for the perceived lack of power? If your truck can't make it up a small hill, electronic ignition isn't going to solve your problem. I think you have other issues.
I have a 216 (unrestored), 3spd, 4.11:1 rear end with breaker point ignition and it drives 60mph all day long up and down any kind of hill you want to drive on.
Have you verified that your vacuum advance is working? What sort of compression do you have in the cylinders? Is your clutch worn out? What size tires are you using?
All of those things can affect the performance of your truck.
Mine couldn't climb hills either and could barely go over 30mph. It turned out the clutch was slipping and it had ridiculous 15" rims and small diameter tires on it.
Once those two things were changed, it could be driven in freeway traffic at 55-65mph.
Before I did anything else to the engine, I'd do a compression test on all cylinders. Your engine may be worn out, worn rings, burnt valves, or who knows what?
If that checks out, I'd statically set the timing at 0deg TDC on #1 cylinder and see where the BB is after that.
