Found a complete ‘69 340 near me, but looks pretty rough. You guys think it can be returned to its former glory? As far as I know it's not seized, seller says it ran when it was pulled 6 years ago… still working with him on price, wanted to hear what you guys thought… What would you pay for a 340 in this condition?
Pull both valve covers and the oil pan for a look. You may want to remove a main cap and rod cap to check for signs of bearing damage and crap in the bearings. Look for metal flake in the pan.
In the valve covers look for undue rust, broken spring or a dropped valve.
Many engines have been sold as "running when pulled out." Yup, knocking like heck or misfire like crazy.