If going to the 4 valve setup as described by fallowdeer above:
The rationale for having all 4 valves on the RH fuse wall is to allow the PIC to easily see and reliably operate those valves at any time.
However, this mean running the feeds from the LH tanks to the RH side of the fuselage. If doing this, ensure there are no undulations in those pipes, as any high spots may contain air, which the fuel must makes it's way past.
My understanding is that most multi-tank setups may experience uneven feeding from L and R tanks, for a variety of reasons.
I had uneven feeding until I removed undulations from those pipes. The result is still uneven, but now far less so.
(I should add that at no point did uneven feeding affect engine performance.)