Hi Chic,
Your model looks great, Have you tested to see where it balances?
If you're coming back to Control line flying, it's probably worth having the CG forward of the 2" called for on the plan.
6oz sounds high to me, the amount of balsa removed to be replaced by plastic wound hardly even be 1oz, and you've replaced it with good detail which would probably be nearly as heavy. I would guess that a muffler would probably be around 1-1,5oz.
I'd suggest you have a trial balance to see where the CG actually is and try some weights to bring the cg to 1" from the LE for your initial flights.
Good luck with it.