Don't use a compressor. You've got plenty of compression with all the gain the 6505+ is making. Compression will make it harder for you to cut. Also, don't worry about outboard EQ just yet.
The "nasally" tone is a good sign. It's what makes you cut through in a band setting. It may sound thin and honky by itself, but with the bass and the second guitar and the kick all together it will sound enormous.
Regarding the Tubescreamer, set it so that the "Drive" is at 0, the "level" is at unity gain, and adjust the "tone" knob to taste. That will tighten things up a bit and remove some of the top end harshness, but give you more "focus" to your core tone. It does really help. It also lets you run your gain a little lower with to get more punch.
Punch is really what helps you cut through; a compressed "plays itself" sort of tone is loads of fun at home, but gets buried in a band context.