Reply to "What would you motor guys do?"

the block deck surfaces need to be checked for warpage before you do anything, the head deck surfaces need to be checked if you plan to re-install them

IMO you'll see an overall performance decrease if you replace 351C 4V heads with Edelbrock 2V heads. you may notice a slight low end improvement but there's no way the midrange & up will be comparable

definitely get the head gaskets repaired before any(more) damage is done to the block & heads! have your factory iron heads vacuum checked for valve seal, maybe even dis-assembled & inspected for valve guide wear? consider new 1 piece stainless steel valves to prevent a head separation catastrophe, have new stem seals installed & put them back on with the Airgap manifold if you think it'll fit under the cover or maybe you don't mind if it doesn't?

or just slap the Eddy heads on it & go...

hopefully you don't find warpage on the engine block deck surfaces or it has to come out for machining. IIRC up to .006" warpage is allowable with composition gaskets as a repair, only .003" allowable with stamped shim stell gaskets. if using MLS check manufacturers info for proper surface finish requirements & warpage allowance

your headers will bolt up to the Eddy heads but you'll need to verify that they'll seal by comparing each side to a gasket. the heads may allow use of a 4V exhaust gasket that will seal on the headers, 2V gaskets may not have enough material on one side of the 4V header ports to get the job done... check it out