1988 535i RESTORATION

I just bought a 1988 535i for 850 that runs good but needs work. Not to familiar with bimmers but can do the work myself with a little insight. Question is what should be done first as general maintanance. Should I replace timing chain and what should be replaced. The car has 145,000 miles on it. I know it needs a muffler because there isn't one on the car and a power steering pump or so I think it does because that is screaming at me. Any suggestions on other repairs that should be done would be greatly appreciated.