That depends on a lot of things:

Here in the US, your Herr Mustang does qualify for RCCA Open (specific class determined by the engine you install), and might qualify for RCCA SSC (depending on the wing you make for it and the engine you use). But, it doesn't qualify for Scale because it doesn't meet the rules.

All of the RCCA rules are here:
http://www.rccombat.com/asp/rules/rules.htm

If you aren't in the US, or aren't using RCCA rules, check the rules that are in use where you are to determine if your plane qualifies.

Another thing you might want to consider before you spend time or money on getting your Herr Mustang to qualify for combat is that it will not survive the rigors of combat. Even if you do build a state-of-the-combat-art wing for it, the fuselage is still far too fragile.

HTH,
D