The first thing I'd look at is the input voltage range of the electronic ignition.
Having said that, seven digital servos and lighting is a fair load.
My preference would be to use something like a two to four cell LiPo,
and, if needed, a 10A voltage regulator (BEC) Castle and others make such critters.
There are servos available, as well as receivers that can operate at voltages higher than the traditional 4.8 vdc.
Others prefer to use LIFE. Depending on the current drawn by the lighting, a 3,300mah LiPo may be OK as a minimum.
A real problem with NiCad and NMIH batteries has to do with voltage drop under short term high current loading, and the difficulty some have in determining the charge state of the batteries. The older analog 72 mhz RX's and analog servos are/were not as sensitive to voltage drop outs as the digital 2.4ghz RX's with digital servos.