Hi Jeff,
I "bin dare 'n done dat" you are in a similar place that I was in 2004. The details differ but in many ways it's the same place. It's a trap, and one that has taken me nearly 8 years to get out of (it's still another 1 or 2 months before I'm completely out but I'm now confident that I will make it).
Eight years of which four of them were essentially just the boat sitting as I had to deal with other commitments or because I was just too tired when I had time and was unable to motivate myself to put on my overalls and get to work. This whole project has just been me, with very little help from anyone else and few cared whether I succeed or failed. I came very close to losing my boat and the possibility of ever sailing on my own boat again. And this, even though I knew and loved the life style as I had been living it since 1989.
In my case, it was an unavoidably large project (if you rip 2/3 rds of the bottom of your boat out, you have a large project on your hands) but my tendency to do everything as right as I possibly could plus the "well while we are here...") mentality which comes very natural to me, led to the taking on of literally hundreds other projects. Each small and insignificant on it's own but they all add up.
What I should have done was be clear about what I wanted to achieve right from the start (which was fix the bottom and convert to junk rig) and stuck to that. Actually, I did not even need to fix the bottom, I was talked into it by others, none of whom did any of the work and those who committed themselves to help, once they realised just how big a project it was, they quickly found reasons to be elsewhere.
Jeff, your situation is similar to where I was. You have a good basic boat that has a few problems but is otherwise in good shape and can be made sailable without to much effort if you can put aside getting everything just perfect before you go sailing. As I understand it, you have just two main issues. An engine/tank issue and a rig issue. I also understand that realistically you are intentionally going to be sailing a lake. Bearing that above in mind and what I have learnt in the hardest possible way (and assuming your goal is to get sailing), if I where you, this is what I'd do.
The engine: It's a small but will do the job. If it's now in good nick (I know you had problems) and it's going to be reliable, pull the engine, pull the tank. Fix the tank properly (I don't believe the West epoxy will do it, the metal needs specific treatment if the treatment is to succeed.) and put it all back. Don't make modifications that are not needed but tidy up the wiring (I believe you said you needed to do this).
If the engine is dubious, forget about it. Get yourself a 9hp Yamaha with remote control, make or have a bracket to put it on. If you need more battery charging capability than the Yamaha can provide, get a solar panel(s) and an MPPT controller for it. You also/or get one of the Honda Inverter gensets.
I don't like outboards as propulsion for a yacht but it's the quickest way to solve the problem right now.
The Junk Rig: You know what you have to do here now. The fastest and most straight forward is the HM sail that I did for you. Every inch of the way has been mapped for you. All you need to do is get 4 odd roles of Odyssey III and start cutting and sewing. The mast you now have and the battens are straight forward.
If you cannot resist the lure of the Fantail type sail, it's a little more complex and the sailmaking will take longer but I'd still use Arne's method to do the camber. Given that you are going to do a lot of your sailing in light winds (at least at first) put a decent amount of camber in. Your hull type needs it.
The above will get you on the water ASAP. Then you will have the leisure to sort the engine (if you still want to) and other things out and make things exactly how you want them. As I understand it, you will bring Seablossem home at the end of each sailing season. That being the case, going forward you can plan projects for each winter, slowly making Seablossem into the boat you want and still have the pleasure of sailing each summer. You will also find, that as you sail, your ideas of what you want to do and need to do will change and what you think to want/need to do now, may not be it.
PS: Arne's suggestion about the outboard tank is also good.