listening rooms

would seriously consider running compression drivers in a volume this huge - you have a LOT of air to move therein

Are you asking what size room would be good to build inside
your shop building?That would give you different suggestions.

some clearification might be needed,i dont have to use this whole space,i can readilly put up walls lower ceiling etc.

If you are going to use the 70 watt monos you will need to shrink your room to something like what I recommended previously. If you put up walls you want something sturdier than just sheet rock if you want to hear bass.

The "Master Handbook of Acoustics" by F Alton Everest has exactly the info you're looking for.