Before you start on the governor, remember that it was working before, so it's most likely something you fiddled with. Try pulling the vacuum hose off of the modulator for a run. That should give you a "slamming shift". If that happens, then maybe you need to adjust the modulator.
Otherwise, is it possible that the linkage is somehow off following the replavcement of the NSS? Can you start in 1 and manually upshift?

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Prost!

I can't manually shift into anything. I've been having some trouble locating the 30mm deepwell socket that's needed to remove the nut. I just aquired the socket the other day. I'll try to use you're advice and I'll let you know what happens.