I haven't done a gearbox only removal myself, but . . .
Me? . . I'd raise the car via the rear hoop for a few inches & install jack stands.
Loosen the engine mount bolts (best to take the top ones out), remove the two long skinny bolts through the rear g/box mount and then disconnect the lower links and drive out the half-shaft roll pins . . should make it possible to lower the gearbox with a floor jack onto your wife's footstool or an old tyre.
Also, the rear gear change tube, of course, and the speedo cable if it looks to be vulnerable to damage.
Then the bell housing bolts are last on the list but disconnect the battery because the starter will be dislodged.
Have I missed anything?
Ask Richard if/where he found some flywheel bolts.