I fitted the two pieces together to re-check my measurements for the umpteenth time! I came up with perfect length measurements.

The mating hood that I picked up unfortunately had a huge hole cut in it and a Corvair deck lid set of louvers was pop riveted to it. Looks like I'll have to weld in a patch of about 2" wide by 25" long.

Looking at the fit of the grooves in the hood with the two pieces, they don't line up so well. I think that I'm going to have to channel a section out of the extension piece to make it fit correctly.