No idea what those are for... but a 68 uses #330265. They list for Chey Nova 68-69:307-327-350 and Camaro-1967 through 69:302-307-327-350 (except 1969 Nova and Camaro:302-307-327 or 350 with air conditioning)....Straight from a NOS box....Bracket is stamped 0268 and comes with two straps(cables) one short and one long...I still have the orig set up on my 68 327 Camaro w/air..... I have some of a recall letter for a 68 Camaro dated from 1972...
Strange thing is the drivers side used the bracket and the pass side used a cable wrapped around the exhaust manifold....Wonder how many manifolds were cracked from reverse holeshots....

First time I removed mine I was putting on a set of headers...backed out of the drive and ripped both motor mounts right out while boiling the tires....full throttle ride till I figured out how to get the engine calmed down...(put it in neutral)...LOL.. L30's can really haul a$$...
Steve