I still have ribs for templates too. I bought a 10" band saw last year to cut them out and I wish I had it many years ago. I use it all the time for many other things and more than I use a dremel tool. It's a Craftsman Model 119.214000. It's all metal. I think it was around $100. For a few it's fine to saw them out but I made a bunch for my use and I ended up making them on a CNC milling machine.
Laser is even faster but it leaves a burnt edge that I sand off where it gets glued.
You have some choices when it comes to plywood. SIG sells there 3 /32" (.093" ) standard 3 ply that is real close to what the original ribs were made of. Midwest has the same 3/32" size with 5 ply but it's much heavier and its strength is almost Omni directional. For the engine mount I recommend that you use the Midwest 1/8 (.125" ) birch 5 ply, instead of the 3 ply like the kit had. On the engine mount where you cut out for the engine, wick some thin CA in to the edge. Seal the engine mount area with finishing epoxy before you cover. This make the engine mount area rock hard and much stiffer. Several hundred flights and hardly a mark where the engine sits. Only had to tighten a few times.
The two square holes in the main ribs for the servo mount were move closer and the rear one was raise slightly for a better angle to the control horn. Lay out your servos and optimize it for you.
If you use carbon fiber tubes you may have radio range reduction on 72 MHz. Others builders please let us know if you noticed this on an all CF tube construction diamond dust. Spread spectrum it should be fine.