ORIGINAL: combatpigg

I think a rib every 3 inches gets the job done OK with this size plane. A 70% size copy of your plans ought to give you what you want. If you want speed then figure you don't want the wing any fatter than 3/4 inch, so this makes building the wing more challenging as you go for ''thin-ness'' Assuming a 7 inch chord, if you really want some speed a 5/8'' thick airfoil is more like it.
I've built a P-51 like this with a flat bottom airfoil, full depth hard balsa spar that was built directly over a 1/16'' balsa bottom sheet. The wing's leading and trailing edges were slivers of hardwood and the ''riblets'' were fairly thick balsa scrap. The whole works gets sanded with a ''long board'' before it gets the 1/16'' top sheeting. 1/16'' balsa is capable of slight compound curvage, but I sheeted the top with 2 seperate pieces. Your Q350 wing will be constant chord, so 1 sheet for the top will work...but it's more hectic to make all those little glue joints in one fell swoop. It's easier I think to sheet the top in 2 seperate operations.

I've found that 350 mah NIMH packs and HS81 servos work well with ''.15 size'' planes. A 3 oz Hayes tank is a nice size that allows a fairly slim fuselage with some extra space for padding.
Otherwise, a 2 oz Hayes tank will allow you to stuff the battery way up front if you end up with a design that has a short nose. This is a slight ''pitfall'' with scaling down some designs because the engines get disproportionally lighter as you drop down in size. The tendency is for tail heaviness to creep in.