The Nova parts WILL work, although, it may take a bit of fiddling. For starters, the threaded through stud on the Nova bosses look to be a little larger diameter than the through hole on the Trek downtube. Would have very carefully step drill the downtube to match. If the contoured base is made to fit a smaller diameter tube, you simply take a half round file, and adjust the contour a bit. It really isn't structural, so no issue.

I may have an unused set of these in a drawer somewhere. Will look tomorrow.