Hey Adam it looks like you're off to a great start! To answer your question, most folks here buy their goose guts. There are guys that make their own though...It can be done. As you may be finding out, different guts will run better with different barrel and insert bore diameters, lengths, and so on. As we say all too often here, everything affects everything!
I would personally advise you to stay away from laquer. It is a very weak finish and there are much better options like spar varnish. Laquer is quick and easy but it just doesn't hold up.
Only other critique I'd offer is that you might want to reconsider how you're setting your bands. With a good portion of the band sticking out from the end of the barrel to receive the insert, you're losing a lot of strength and glue surface. Your insert will self-center in the hole in the barrel when you use a gutsert, and the call will be stronger if the tenon and the band are the same length.