Eric, my personal suggestion.............
I just put a BGF slant head 66cc on a bike last week that had been sitting in a box in my shop for over a year, I didnt do anything to it internally, never pulled the head, only put a Manic ported intake on it and made up a not so good exhaust for its breakin miles, this engine was put on the bike and I had it running and was riding it in about 3.5 hours, the bike already had a sprocket on the rear wheel and the throttle on the bars when I started but that was about it.
I said all of this to simply let you know that the problems you have had with that engine are not typical...... I have 4 engines and currently have 3 bikes running and they all started up the first time I popped the clutch after installing them on the bikes, and then I went for a ride down the road within minutes of them busting off for the very first time, and this is the typical story of these engines for the most of us.
If I were in your shoes I would go on ebay, look up BGF, buy just an engine ONLY for $80 + shipping mount it on that bike and start riding it that same day and I'll 99.9% Guarantee that would be the case if you did that very thing.......
That would be way cheaper than the prebuilt set up and probably just about as good for what you are wanting the bike for..........
Just my $.02 nothing more nothing less.........
just get an other engine and this time next week good ole dad will be riding his bike.........!
Sincerely, Shan
Also thanks for all the help...I'm just not as dedicated to this as all you, but I did put in my fair share of work on it. I just draw the line to having to tear open a NEW engine..I don't mind the other stuff, but I'm, not pulling heads or pistons....