The recognized good method DVD series (to some folks) is the Gibson Learn & Master Method set. 10 DVD's of lessons, a book and 5 play along CD's. Before you cough at the price, two lessons with my teacher cost what this set does. It's not a lot to invest and you'll see if he takes to it. Then you can plump for lessons in person or Skype to advance.

There is no "convert from Uke" per se. The chords are the same, the key is different (guitars are tuned E-A-D-G-B-E while anything but a baritone uke is G-C-E-A and the G is 're-entrant" or high where as the guitar goes up in pitch only.) The C chord on a guitar has one more finger (for those 2 extra bass strings) and is an F, I think on a ukulele. HOWEVER, no problem to switch over as the principles are similar. You just play each as its own instrument. I switched from soprano uke as a kid, to baritone (Dad would always buy the BIGGEST of anything, so I ended up with a tenor recorder which I hated and a baritone uke, which flummoxed me as a kid until I figured out it was a mini guitar, then I ended up with a guitar as a teen, playing folk.) Never had an issue==one taught the other but you just had to adjust what you did.

I don't think there is anyone who bothered to write "guitar for uke players." Just go with it. As the fingers need stretching on the wider guitar fretboard and since there are two extra strings, just learn guitar.

Guitar makes Uke easier, not so much the other way but it helps.

While you are at it with the Garrison G-30, restring it and keep it humidified. I think a friend of mine had one for years, played a 12 string version. She's a string player (busks violin) but this was her guitar as well. I think it's Canadian.