That's only kinda roughed in, it's not welded yet or anything, as it still needs more stretch . . . but it's easier to do in segments so I know it's fitting and aligning OK as I go.
A normal base set up fits under that 560 stretch pretty well, it has the screws in as it sits . . .
I'd have to modify a front pedestal a bit to fit the modified front portion of the 560 stretch, but it should go much nicer on the 840 stretch.
This is going to be one of those solve the problems as they develope progressions.