I am going to be doing some pond expansion

, and for a several week period I was thinking of keeping my koi in a temporary show tank.
I have a 6-foot show tank, and I have 6 koi about 20 inches long, 1 koi about 10 inches long, and a 10-inch goldfish. If I bought a proper filtration system, could I keep this many fish in there? Any thoughts on what type of filtration system I coud use with a show tank?
Alternatively, I could borrow, rent, or buy a 2nd show tank and put half the fish in each one?
Any thoughts, advice welcome.
Thanks,
Rockman