I'd have thought with a little adaption that will be fine

mine live very happily in an old wooden crate with a pop hole cut in the front so they're not fussy.. From memory I think you need about a foot of perch space per bird (roughly, it will depend on the size of the hens you choose obviously) and a dark place (put shutters over any windows maybe? will be a bit more secure but you can still peek inside and see how they're getting on, that they're all there when you shut up at night etc) / nest box for them to lay in (about 1 box for every 3 hens I think, mine isn't seperated into a ox they just use the darkest corner).. the perches should be higher than the nest box(es) as they like to sleep at the highest point so if the boxes are higher they will sleep all bundled up in the box and fill it up with poop overnight which makes a bit of a mess of your eggs..
I'm not sure how many it could house, it would depend to a certain extent on how you adapted it. My 3 are in a ~4ft by ~2ft crate and it could easily take another couple if I had the outside space to accomadate them (they need at least a square yard of outside run space but more is desirable) so if you have the outside space maybe 6? they won;t generally spend much time in the house during the day and like to sleep all bundled up snuggly together at night... Another couple of tips, line the bottom of the house with some old lino or similar as this will make clearing out alot easier and make a run you can easily walk into.. makes a big difference with the day to day maintenance as you can pop in and sort food/ water/ clean up and also means you can go sit in there and have a chat to your girls (if they're anything like mine wear old clothes tho

they love to jump on my lap for some treats and some climbs right up to my shoulder for a good look around her domain..

) last tip, if possible design it so you can open the pop hole in the morning and let them out without going in the run.. that way you can pop out in your slippers first thing and not make a mess
