Hmm... an inch of space, but housing males. Personally I would cover those bars with 1/4" hardware cloth just to be on the safe side, even though males are less inclined to squeeze out than females.

As for putting the three together, after cleaning that 'new' cage thoroughly, I would introduce the three males in a totally neutral area, such as the bathtub. Put a towel down so they don't slip and watch them closely. They'll probably scuffle, so that's ok. Basically, use your own instincts to make the call on whether they'll be alright together based on how they interact in the tub. I've done this with females and it works great, but I'm not sure with adult males... Hope things go well!