Its been a while since I looked at the regs, but you may want to consider quickly getting your Helicopter ATP and then immediately jumping to get your airplane ATP. It used to be that if you had a rotary ATP, it required much less fixed wing hours to get your airplane ATP. That was years ago but if that rule is still around, it may save you some time and money. Then again, it may not be necessary now. Good luck.
Um, its not hard to look at the FARs before giving advice.