Thank you for the replies. Several things I want to ask:
1)Who make a good 13oz/14oz 3-line tank?
2)Did you see the Slimline filler I listed above? It doesn't have moving parts to fail, and will work with the two-line system.
3)As I've been reading more and more this morning, I'm leaning towards the 2-line set up with my existing tank, and just using a 'T' fitting with a fuel DOT between the line from the tank-to-carb. Yes, I understand I'll have to close the throttle all the way to fill. Are there any other drawbacks from this setup I need to be aware of?
Nothing here is perfect, but I'm trying to weigh everything.