Alot depends on how hard you push the amp. Any 30+ year old vintage amp is going to be at risk for failing even if not pushed hard unless it's had all the electrolytic caps replaced. And you better know how to use the Standby switch.
The Model T will stress 6L6GCs well beyond their ratings. There may be one or two varieties available today (ask the Eurotubes guy) that can withstand the abuse, but you would need to find a tech that has done this for a touring band. It's a little different than your average tech that mostly services local bands. Don't take any vintage amp on the road without a backup.