An '85 will have almost no advance built into the distributor. That was part of the old-style smog controls. Depending on the calibration, you may see only four to six degrees of centrifugal advance.
You can buy HEI recurve kits from Mr. Gasket and other sources; any big speed shop will have something. The HEI is very easy to curve compared to most distributors; all the mechanism is on the top, and you don't have to disassemble the entire distributor every time you make a change. You want a fairly smooth curve from idle to 3000 RPM or so. Some aftermarket distributors still come with 1950s-style hit-em-hard curve jamming 12 or more degrees in by 1500 RPM, which worked okay with a rich mixture and 105 octane regular, but doesn't work well on street gas.
A properly curved distributor will have zero to four degrees of static advance, and the curve will be *just* below the ping limit the rest of the way up. Most street engines are relatively insensitive to advance over 3000 RPM. You're not going to get a perfect curve without a lot of work, but a few tries will get you close enough.
When you make your full-throttle runs listening for ping, try it both with the windows up and the windows down; it may be easier to hear one way or the other.
You don't care what the actual advance numbers are; the car will tell you what it wants. Then you can put the timing light on it if you want.
Keep a written record of what you're doing; it will keep you from overshooting calibrations and wasting time.
You also want an aftermarket adjustable vacuum advance. The primary purpose of the vacuum advance is low-throttle cruise, like rolling around at 35mph in town or 65 on the freeway. When you push down on the throttle vacuum drops, and so does the advance, down to where you set the centrifugal, if you get it all set right. A properly calibrated vacuum advance can give you several MPG in most driving; it's worth your time to work on it a while. The money you save on gas will buy more car parts.
