There are always lots of material sizeing issues when you scale up models. In this case since it's a Bee type I think you'll get away with a lot of liberties in most places. One area I would go a little overboard on would be the wing spars. The new model will be much heavier and would probably benifit from using oversized spars or sub'ing in a stronger material for the 2x sized dimensions.

Making a take apart wing has a few special needs too. On a Bee the obvious spot is at the dihedral break but there's not a lot of structure out there to work with. You'll need to add bits to ensure the spars carry through the load correctly and that the covering doesn't pull the open structure ribs all out of shape when it shrinks and that theres a decent method for pinning the tip panels in place so they can't move out of alignment. And you need to do all this without loosing the character of the Bee or making it overweight in the wing tips.

For the most part at this size just using 1/4 sq to sub for 1/8 sq is fine as long as you're not planning on using a lawnmower engine. If you stick with the Bee design being powered as though it was a SAM type of old timer that would indicate that you'll be using a 40 to 60 sized engine. For that size using double sized wood will work as a general rule. If you want to use all that wing area to plunk in a 90 to 120 then all bets are off and you'll want to upsize the wood in some areas and use the standard 2x sizes in others. The tail especially will be critical if the engines are pulling the Big Bee around at higher speeds than a normal Bee flies at. Either make them thick enough to handle the loads or consider using functional rigging as a lightweight and high strength option.

This is all pretty general. If you persue the project come back with specific questions and be prepared to post up pics or scans of SMALL areas (for copyright reasons) of the plans to better show what your up against and the folks can help out in more detail.