Engine rebuild

if you've a spare engine then just top&tail it to have a looksee? nothing ventured etc.

also, have a budget....

if the cylinderhead is flat then don't bother with a skim as it allows later machining if needed.
as to valves, once the head is off, remove the cams & followers (but leave sparkplugs in) then invert the head so it's chambers are at the top, place on a flat table. pour some petrol in each chamber & if the valve's seating is good there will be no liquid leakage into the inlet or exhaust ports
although re-seating the valves is good practace & cheap so while the head is off......

when the sump is removed this gives a chance to inspect the crankshaft, plastiguage is your friend if you loosen bearing caps.

how far you dig is dependant on your budget, how much are main / big-end & thrust bearings? what about piston-rings (or a re-bore & pistons?) do you get the cylinder-block acid dipped to remove the gack in the waterways? maybe re-surfacing the headgasket surface or line-boring the crankshaft's main-bearing tunnel?

sorry, off on a tangent

Rich.