Having just replaced that same gasket on a 20hp within the last two weeks, hopefully I can help you. When I went to put it back together, I was wondering how to position that governor lever/shaft so the tab would engage the centrifugal weights properly. After looking at it, I decided to let the lever hang straight down as I slid the engine base/oil pan back onto the crankshaft. I was a little apprehensive the first time I fired it up as I didn't know if the governor would work....but it did. Of course I had the engine turned upside down when I reinstalled the base/oil pan.
The other possibility is that you didn't reconnect the two springs properly. When I went to reconnect them, I was sure where they went, but since I had another mower with a 26hp B&S nearby, I checked it just to be sure.
Does the governor lever move if you move it with your finger?
