If its ammo availability that worries you, there's other companies making military load 150gr .30-06 for the M1 Garand. I'd not go .308 solely for that reason.
If, however, you are set up with .308 as it is (or you already reload it), then a .308 Garand may be a worthwhile investment.
Ok, I'm not smart on 30.06 ammo. What's the difference between the military 30.06 load for the Garand and just regular 30.06 ammo I use in my Remington?
In an aircraft, the only time you have too much fuel is when your on fire and the only time you have too much ammo is when the house is on fire.