jpuke,
I have built two of the 1000 "Big Boss" series for rubber free flight. The JU-87 Stuka, and the F6F Hellcat. I really like the larger Guillow's scale war birds in the 1000 and 400 series. Some will argue that these kits are too heavy, and they don't fly as good as other kits deigned specifically for rubber powered free flight. Yes, to some extent that's true. But those little free flight specific kits don't look as cool as the bigger warbirds.
The bottom line is your kit
will fly.
Just a couple things to pay attention to:
1.
Cut weight where ever you can. You mentioned that you've already cut the lightening holes. Sanding both sides of the balsa prior to cutting lightening holes, or removing from the die cut sheet is preferable. If you sand them now, you may do more harm than good if you break formers and ribs.
Use your glue sparingly, glue weight adds up fast.
Scallop the formers
between the stringers after fuselage assembly, this shaves weight, as well as making the finished model look better too.
2. On the Guillow's side view blueprint, you will find a
free flight point of balance. Pay close attention to this datum point. Also try to make sure the left and right wings are built
exactly the same. ( weight & airfoil shape are symmetrical)
3. You mentioned that you have 1/4 inch rubber. Excellent! The gray spaghetti in the kit isn't too good for bigger models. Use your 1/4 in. stuff.
Armor All for cars is a pretty good lube, and will get you some extra life, and extra turns in the prop.
4. Test glide, test glide, test glide. Once balanced and adjusted to glide nicely, gradually build up the number of turns in the prop.
Your P-47 will give you some nice flights. Don't worry about the silkspan in the kit. It's really good stuff! The 1000 series kits come with medium or heavy silk. It's very easy to work with, and the little added weight is offset buy the added strength it brings. All the best for a sucessful build, and fun flier! Looking forward to your build pics.
Pauli72