If there are no specs, how are you planning on giving them power? 110rms at 2ohm is a alot of power for some 4 inch speakers for which you have no spec sheet (e.g setting your gains blindly). Magnet size also isnt the only factor. Bring in the math and you can argue your 8 4" drivers will have close to the same surface area as 2 8" drivers but again it's not what you think (xmax, sens etc also are factors). even if you install 20 4" drivers, what good will that be if it doesnt sound good? I hope you are getting the point. There's a reason why you have separate drivers in a component setup each designed to play certain frequencies and fill in the gaps.
You may go ahead and wire up your speakers in parallel with your amp on your home bench test area. The math is good. listen to some songs and see if it really is the sound you are looking for.
Which city are you in btw