The deal with the tank and a mini tub actually has nothing to do with the suspension, it has EVERTthing to do with the tail pipes.
when you mini tub the car and put a 335 rear tire on there is no room for the tail pipe to pass between the STOCK tank and the tire. therefore you must narrow or section the corneres off the tank.
the suspension has no bearing on weather you need to narrow the tank if you ran exhaust dumps infront of the rearend you would not need to modify the tank.
here is Rogers 69 with Speedtech rear, 345/25/20 tires and 3" tail pipes with a modified stock tank.
