I’m confused. Great room, 14’ ceiling, why not use the existing ones???
What model are the existing ones? If you do not know, search the internet 'klipsch speakers', find out what they are that way.
Those amps, EL-34, what specific amp are they in. You want very efficient speakers (high sensitivity ___ db 1 watt/1 meter to drive them in a large space with tube amps. Typically horn speakers are used as they are the most efficient, thus easy to achieve large volume levels with tube amps.
Less efficient speakers, you will probably want to change to a SS solid state amp, or a hybrid, part tube/ss power stage.