I think it's worth a try now with careful supervision. Most roosters are very family oriented; wait with the hens while they lay eggs, sing the egg song with the hens, and sometimes help out with chick raising. At the least, they leave the chicks alone but keep a watchful eye. There are some criminally insane roosters out there. Generally those need to be isolated because they can't live nicely with the flock. Most of what I do with my rescue is work with roosters. They really just want a job to do.
Another thing, the rooster daddy I was talking about was a beta male. The alpha male kept to the rest of the flock but never bothered the chicks. Oh! And recently an OEGB hen hatched a single chick and has SEVERAL beta male OEGB roosters helping her. That mama and baby have been with the flock since day 1. (These are not my chickens.)