Should I get another 480watt qb or go for 650?

I'm growing in a 4x4x7 and indeed to upgrade my lighting . I have a 480watt qb 650w is designed for my space . I can get a 650 but leaves the 480 somewhat null and void unless I decide to use it in which case the canopy will be very uneven and the bill extortionate.

Considering just buying another 480 and running both

One 650 seems like it’d be enough. (2) 480s might be too much juice at full power? With QBs you’d probably be above 1500 ppfd
CO2 supplementing?

How do you fit your ventilation system?? I have a 4x8 tent and I tried to run 2 650s in there and I couldn't run my 8 inch ducting without offsetting one sides lighting. And my 4x8 is actually oversized in width too to about 56inches. I could do one of two things. Run the ducting over the top of my light bars or run the ducting and everything outside of my tent which is my least desirable idea since it changes direction of carbon filter from pull to push and also makes it a little less concise and hidden