I got a new battery for it and actually got it to idle today...tach doesn't seem to work, so I'm not quite sure what rpm it idled at, but it actually idled quite nicely.
Now, I made a rookie cb750 owner mistake...I checked the oil after the bike had been sitting for a very long time. It seemed nearly empty! So, I added a fair bit of oil and checked the dipstick...perfect! Long story short, oil was spewing everywhere....Now I know to check the oil only after the engine is warm on these bikes. Oops!
Other problem I noticed was that my gas tank seems to have a leak, which is a bummer. Going to have to get that resolved before paint...