Give Marantz tech a call as the SR5007 has 4 ohm grunt capability. In the meantime, Crutchfield specs the P363's at 8 ohms.
A recommendation, if you can, up the quality of your center channel choice. In my opinion, the most under looked and under respected speaker in a system is the center channel. Some 90% of the sound dialogue goes through the center channel. My opinion, the center channel and the sub are the two most important speakers. Next are the mains and then the surrounds.
A suggestion, build your speaker system by choosing a high quality center channel complimented by a similar quality powered sub; your Klipsch choice in a sub is good.
If you have to budget, make the mains and the surrounds the pivot point and upgrade the mains and surrounds at a later time and point. Yes, this flies in the face of convention as convention tells us to concentrate on mains first.
And off the wall suggestion, marry a pair of Klipsch RB-61 II's up with a RC-64 II.
FWIW, this forum turned me onto Acoustic Sound Design
and they have killer pricing on B-stock and maybe you can work a killer deal with your infinity choices. Also, in my opinion, the SR5007 is an excellent match for your posted choice in speakers.
I priced out your speaker choice at $1,600.00. I'm sure with phone calls you can get a better price. Acoustics Sound Design online prices this Klipsch RB-62 II set
at $1,500.00 and I'm sure with a phone call, you can get a better price.
I would see what price you could work out for the RB-61 II set and upgrade the center channel to a RC-64 II. Marry these speakers up with a Marantz SR5007 and all you need is a flat screen and a bag of popped microwave popcorn.