6X cylinder heads on 68 350?
 

Hoping that someone out there can chime in with some info. Will a late 70's 6X cylinder head install on and operate normally on a standard bore 68 Pontiac 350 block? Restoring a 68 Firebird and have been offered a set of refinished 6X heads for a good price but want to ensure they will work without issue prior to purchase. Thanks for everyone's time that has any info.