I don't know if I'd recommend them for the backbox since they dont come in a frosted, but the most incandescent-like light of the many I've tried are actually the ablaze 3-led WW. I only use them where you can't see the bulb though because they have no dome. I also usually have to order more than i need because there are always a few that are either too cool or just a sickly yellow, but they usually they have a great glow and decent brightness.

My second choice for the pf is the Comet 2Led WW, though you might want to move up to something brighter like the 5050 for the backbox.