Usually the engine has to be dismantled first to figure out what's needed. You're going to need, if things go really well, standard piston rings, and standard rod and main bearings. The rods will be the narrow ones used on the eight bolt cranks. The most expensive parts will be a camshaft and 12 lifters. If the engine has steel timing gears, re-use them. I've never seen them wear out. If it's got fiber gears then you should replace them too. All of the valves will be good more than likely, the guides too. Strip the rocker shaft, but probably the rocker bushings and shaft will be fine.
Check the head thickness so you can work out the compression ratio. It's probably a low comp engine, most were in that year. If it was mine I'd be prepared to mill a bunch off the head to raise the ratio. Mid 9's would be great and make a big difference.
And check the ring and bearing prices against buying two sets of each for a late B20. Sometimes its cheaper.