If it's all new to you, start with the basics and get everything set right. Check valve clearances, soak plug, contract breaker points etc.
If the decomp removed completely and blanked with a bolt? If not, even though the cable is removed you will be able to push it open with your thumb.
Watch hoohoohoblins very useful videos on YouTube, just search for the name to find his channel then search his channel for bullet videos, you'll see the how to on points, clutch, starting, oil change, tappets and so on.