just swap out the shafts/rockers/push rods any springs or retainers that might be rusted up. (318 parts will fit)

clean the rust from the head with a wire brush and shop vac as you brush the rust loose.

just make sure your shafts are on the correct way for each head and the offset is correct on each rocker as they slide on the shaft.

you dont want any loose rust floating around in there when it goes back into srevice.