Timing cover and dress up???

After pulling the cover, inspect it completely. Water cavitation over 30-40 years can eat the alum out and reduce direction and even thin the part so much it could leak thru to the outside. Also check the area to the sides of the timing chain for wear. If someone has run an old timing chain for a long period, you can have dangerous wear there also. If your part checks out, use it. If not use a new one for the 70's motor.
I had to replace a water pump last year which meant I had to pull the bolts that go thru the timing cover into the block. I didn't notice till I got it back together with antifreeze that the gasket broke between the timing cover and the block. Then I had to pull it all apart and of course, I replaced the timing chain as preventive maintaince. I went to Tractor Supply and got new Grade 8 bolts also, I thought it was cheap insurance.