Could someone tell me how to manipulate the two levers on the transmission to put it in neutral? The tranny is off the car but I want it in neutral for installation. Maybe an explanation of how those levers operate in terms of gear engagement would also be useful.

The levers on the transmission should be in neutral when BOTH levers are in the center position, there should be a detent that you can feal when you move them. If the transmission is stiff from setting a long time you may need to slip a cheater pipe ofer the shifting levers where the shifting rods or the vacuum unit connects. I haven't been into a vacuum assisted in way too many years to say about them. In order to get either lever to shift, start by positioning the two levers in the center position so that whwn you turn the front shaft (clutch shaft) the output shaft will not turn when you hold it while turning the front shaft by hand. The reverse low lever will change the rotation when the High second lever is in NEUTRAL and the low reverse lever is moved into reverse. Remember, both levers and the shifting forks and movable shifting gears must be in neutral before checking the gear positions.