Seeking help on floorstander plans for Altec 2459A

Hi all,

I have a pair of Altec 2459A currently on Open Baffles. While I'm not complaining about its sound, my dilemma is I need the space and a footprint such as those used by commercial (Mission, Mordaunt-Short, Wharfedale) floorstanders would be ideal.

Can somebody point me where I should be looking at? This is going to be DIY.

Should it be a Horn type, bass reflex, etc? I have no idea. I hope to get down to 40Hz, if possible.