I'm pretty sure MIDI format 1 is the multi-channel one you're talking about.
GPO will probably import weirdly from your Noteworthy MIDI, since from my experience with it (in Logic 8, might be different in Finale), GPO interprets Sustain and Modulation differently than normal.
Sustain (on non-sustain instruments) = Legato Trigger, Mod. and Note Volume = Intensity / Attack Strength. Sustain works as normal on realistically sustainable instruments, like Piano. Track Volume and Expression should transfer over fine, I think. The different interpretation of Note Volume especially messed up a lot of old MIDI's for me, so look out for that :P