Glad you like the tank and mounting cradle. I've posted some photos so you can better picture whether or not this will work for your build. The rear rack is something I really like and is very sturdy (not for sale) and I've modified several of these so far as they are perfect for a behind the seat gas tank. It is made from a 1960's schwinn front rack, nicely chromed and not much wanted by anybody as front racks ain't cool. A stock rear rack from the same bike is worth a bundle and much in demand, but not the front. Where it originally fit under the front tube I slip it over the seat tube with a large flat washer and small hose clamp under and the same above to fix it at the height I want on the seat tube. I then eyeball the angle of things regarding the axle mounts and figure out how the rack should be bent... take it off and do it to it... the last one whacked with a splitting maul (not the sharp edge) as it is very strong steel and doesn't want to bend. Anyway, that's the rack you're looking at. I like the lines, quality and simplicity of it. (& it's inexpensive!). That tank was a kind of 'proto-type' early version and has no sight gauge fittings. The cradle was made with that rack in mind and can fit either cross wise or length wise. You'd have to figure if it would work with your rack. The cradle is of two basic parts; the heavy aluminum plate under the rack which was made from part of my brother's boat dock materials and is about a 1/4" thick. Above are two sections of aluminum channel bolted through to the plate below. I was still in the stage of figuring out how to hold the tank to the rack and drilled holes through the bottom plate for zip ties to fit through. Those holes could be altered with a dremel cutoff wheel to make slots for either leather straps or stainless steel clamps. Where the aluminum channel contacts the tank I slit vinyl fuel line to slip over the top edge as a cushion... don't want metal against metal, right?
If you think it will work for you and you want it I'll sell the tank, the cradle and a matching funnel made from a mandarin oranges can and copper tube soldered to it. I'll be reasonable. PM me,
Silverbear