At the link is some interesting reading on the Gibbs cartridges.
http://shakeypete.blogspot.com/2009/08/rocky-gibbs-and-his-cartridges.html
Although the Gibbs cartridges were revolutionary in the 1960's era, they never achieved factory status where they might have been an improvement in some cases (pun intended). Gibbs was to some extent trying to outdo Ackley's AI concept with his own ideas. With the 30 Gibbs, which probably made the most sense of his cartridge designs, he even played with front firing cartridges utilizing a long tube from the flash hole and duplex powder loads with fast burning powder up front near the case neck and progressively slower powders (maybe 2-3 different ones) moving back toward the base of the cartridge.
As has been mentioned, the 6MM-06 or the 6-284 are probably better choices today unless a guy just has to have something radically different from the guy across the street.
Years ago I played with a 30 Gibbs rifle by making brass from 30-06 cartridges by necking them up with an 8MM expander button and necking back down to 30 caliber, leaving an 8MM false shoulder to head space from in the Gibbs chamber. What you got after the fire forming effort (done with either cream of wheat over a fast pistol powder and a wax bullet, or actual chamber firing with bullets) was a short necked improved case that didn't due a whole lot more than what the 30-06 cartridge that you started with was capable of. But it did occupy my idle time for a period in my then young life.
IIRC, I lost money when I sold the rifle to someone who "just had to give it a go", but I was forever freed from playing that particular game in my life. Que Sera.
EDIT - I never played the front firing/duplex powder game at the time. I stuck to a single powder and a conventional primer set-up. Even back then front firing and duplex powder mixtures was too racy for my mind to absorb. Today is scares me just thinking about it