I cant think of anything that should cause this, at least nothing with changing oil and filters. So I will toss off a couple things to try. There are no safety features that kick in with low oil pressure or anything like that.
How much oil did you put in? The average change ends up being about 3.5 quarts but not all at once. You have to spin the motor and get it to sump, then you can fill more.
Do you still have the electric start? What happens when you try to start with that?
Check the wires that run from the points, or whatever ignition you have, to the coils. Possible that pulling the airbox off may have yanked them from the coils or ignition unit.
If you can, try to put in different fuses and clean the terminals on the holders. the glass fuses can go bad and sometimes you cant even tell.
Is fuel getting into your carbs? Hook 4 pieces of clear tubing to the drains on the bowls and angle them up. Open the screws and see how far they fill. Should fill to right around the top of the bowl or so.
You can also turn off the gas and lay the plug leads on the head and turn the bike over to check for spark. If you can get spark, then there is a good chance it is fuel related.
The ride IS the adventure. The destination is just to get gas!