From what I've heard, neutered males tend to go with females better than other males. Of course, this is dependent on your male as well as the pair of females. But, I do think it would most defjnitely be worth a try. Most rats will eventually get along with others in the end. Hopefully it'll go well for you if you do get the two females. :3
I would also look around the forum at the stickies at the top. There is one on introductions for new rats as well as lookin atthe Carrier Method. (Stickies are found at the top of each different section of the forums. ^-^)