I am assuming no engine work was done, and you are running oem flat tappet cam and lifters. If so it would behoove you to find and use an engine oil with Zinc Phosphate added, or pour in a Zinc Phosphate additive, as modern engine oil is not generally using Zinc Phosphate any more (it fouls catalytic converters). These older engine need Zinc Phosphate so the cam lobes and lifters do not get wiped out (quickly). My personal favorite engine oil is AmsOil Z-Rod 10/30. But there are also several other excellent oil brands that have Zinc Phosphate in their design.