Nice write up. If you need any info, let me know.

I noticed on the first page, you say that the hole in the reservoir should be drilled with a 3/4" bit. That's for the advanced 3/8" tubing bulkhead, the bulkhead you have pictured is the smaller (Value Bulkhead) for 1/4" tubing.

For the Value bulkhead, I recommend drilling with a 9/16" bit. The hole will be slightly undersized and you'll need a bit of force to jam the bulkhead in. Given that most of the people drill in plastic, then that's not too difficult. Once it's in, it will sit nice and very tight. You could also get away with 5/8" bit and if you're installing into something hard (glass, metal, etc) I recommend 5/8" since it will be harder to jam the bulkhead in.

Here's a PDF for your reference.

Marty