Yellow Jacket EL84's in Express build question

[mike9]

I asked about a TW build using two EL84's in another thread and was directed towards the Express build with some substitute component values. Well today I remembered Yellow Jackets - you know those adapters that let you substitute an EL84 for a 6L6, or EL34. My next thought was how to switch back and forth between the two tube types. Like having the two values available to the tubes via a toggle when swapping out the YJ's with real EL34's. If the leads are kept short as possible and good shielding practiced shouldn't it work? If I'm way off base here please let me know. Life is one big menu of learning curves for me.