How many miles are on the engine, the cam gears are usually worn as well. If your gonna keep it for a while then fix it that way. It is acceptable to use the factory marks to set cam timing, but to do it correctly you will need a degree wheel for the crank, a depth gauge to set TDC as well as a dial indicator with all needed hardware to measure lift at each camshaft, I ran a dyno for 11 years and on occasion did that procedure shopping for horsepower. To be honest the gain isn't worth all the effort. As for the chain with valve covers removed grasp the chain at the center of the gear on top between thumb and finger and lift, if the chain only raises slightly it is still in order. If it lifts a large amount the chain/ gear set no longer fits correctly. The gear teeth will also seem sharp at the upper edges from wear. Setting the timing of camshafts correctly and rolling a chain is the simplest but most dangerous procedure as the failure rate is high for mistake. If the gear is set a tooth late it will have low manifold vacum and be lazy, if it's early it might not bend a valve....... maybe.
Bill