Once that is established locate the X and sound hole locations.

Your choice is how to arrive at the X, i.e., tighten the splay and/or move the X down to accomplish this.

I cant tell from your drawing, but you are using a true layout of the chosen scale length to find your fret positions, and thus the bridge position correct ??? (such as fretfind or similar). You cant simply lengthen the neck by an inch, and then move the bridge an inch and have everything lay out and then play properly -- if you did do this, what would the scale length be ??? (OK .. there is an answer to this, its that the scale length is now 2 inches longer than whatever one you started with - but it probably wont be a 14 fret neck joint) - But is that the scale length you wanted ???

I explain things like this to my students all the time .. the scale length tells you everything .. you cant just move one thing (like the bridge) and say its now a longer scale length because the string is longer .... the math doesnt work that way ...oooooh, he said the scary word ... MATH !!!!

any blatant flaws visible before I continue?

I would get the bridge wings farther across the X brace, Also is the bridge plate what I see under the bridge outline, if so it is rather small.

You might want to read this from David Berkowitz posted in guitarmakers magazine http://www.berkowitzguitars.com/pdf/guitarmaker-33.pdf

Fred