o gauge layout

hey guys. as some of you know I am defiantely a newbie. I got a new catalog today called track power and was looking at some layout options. I like this one with two levels and has a outer and inner loop. on both loops they are using O36 curves. I wanna expand that though to a wider curve so later on when I start acquiring bigger and better locomotives I don't have to buy track all over again. On my outer loop I was wanting to go with 0 72 curves. my question is the size of benchwork they are using with the 036 is 10x7. so If I go with 072 curves does that mean it will have to be like 20x14 ??. ill post a picture of this layout.