Hitec 7955 and spektrum sr3100 work fine with lipo unregulated.
The receiver is rated to 9.6V but Hitec only rates the 7955 to 6V. I know several people that do run their 7955s at 7.4 regulated volts (with a CC BEC) but a fully charged lipo is 8.4V. So if you do go unregulated the receiver is fine, I'm not too sure about the servos.