Not that I'd want to put anyone off getting a rescue cat, they are wonderful and i've taken on many over the years - but maybe if you want an indoor cat you might want to think about a pedigree breed that has always been bought up indoors and never known anything else - or many pedigree clubs have welfare sections and sometimes have pedigrees that have lived indoors and that need to be rehomed.
The thing is with many rescue cats is that often their history isnt known, so there is no way of telling if a particular cat would be suitable to live indoors or not, so, unless the rescue charity actually knows the history, they maybe can't recommend a particular cat because of that. Obviously they are looking for a 'forever' home for each cat, and don't want to see the cat come back again because it couldnt adjust to being indoors. Hopefully one will come along soon where they know the history and would be ideal for indoor only.