Change the rod bearings and cross your fingers!
Someone (not me) came home from a 40mile drive and informed me that the car sounded like a sewing machine the whole way home.
Not enough oil to pump up the lifters.
The engine had 60,000 miles on it.
Put a bottle of slick 50 in and the rest with oil.
For the next 100,000 miles it had a deep thunk, (rod knock)
Only stopped driving the car when I couldn't get the auto trans to shift into druve anymore, reverse was fine.
Moral to the story...
All you have to loose is time and a few bucks.