Hi Marcus,
I must be losing my eyesight in my old age as it appears that your friend Darren's tub has a mistake. In the top picture of frame #25 the outboard most lightning hole looks as if it is dimpled 180 deg. out. Like it is fouling (chaffing) on the front bulkhead. Should that particular lightning hole have been dimpled in the same direction (fwd), as the other two inboard of it?
Its late and I have been crawling around airplanes since early this morning, so excuse me if I'm mistaken!
It will be interesting to note the sale price of SL76/147, as this will be at least some indication of the value of what you will accomplish in the end!
Regards,
Scott