Aggie, like you are with metal I am with wood and have a complete woodshop but even so I bought my darkroom furnishings. For a stable worksurface that doesn't have to be pretty I would go to used office supply stores or GoodWill etc to find a big heavy stable cabinet or desk. Or weld up something from angle iron since you are a metal worker. Those books are decent starting points but are pretty limited on different ideas for darkroom set ups so look around at every darkroom picture you can find.

My dry side is a desk height old cabinet with the enlarger wall mounted at maximum height for ceiling clearance. To bring the easal up to standing height I have a small 15" high box in front of the easal. By removing the box you can do very large projections. The lower cabinet height allows me to sit for most dry side opperations like loading and unloading film and has 8 huge drawers for storage.

If you start thinking "out of the box" you will be amazed at what you can pick up cheap or free that will work. My sink is a large stainless tray from a mortuary (let your mind run free on that one) that sits on several old two drawer filing cabinets. I was lucky on the sink but you can check out restaurant supply stores or call around Camera clubs, stores etc. for used photo sinks. I never used to see these around but lately with every one else getting out of wet darkroom I'd bet you can find one. Other wise the books show you how to build sinks.

The size and arrangement to fit the space you have is always custom. I have had roll it into bathroom size, permanent stainless sink in a bedroom closet size, old tables and laundry sink in basement size, and my full bedroom size that I now have. You are lucky to have all that space available. Add a bunch (lots and lots of) shelves and other storage cabinets and then all you have to do is the easy part, wiring and plumbing.