using a long nut, a fitting bolt 8.8mm in diameter and a hemisphere-like rubber washer we were able to extend the pushrod 'reach' sufficiently to be able to put the transmission into gear. it was still difficult, so may be we need to get more of an extension, but at least we know it works!
we were able to back out all the way to the bottom of the driveway and then come back to roost.
when we try to go into any of the forward gears, it is awkward but can generally be done with some persistence. there is no grinding though a very slight humming while it seems to be searching for a way to get in.
to go into reverse, can be more awkward and there is some grinding then, though once i've even slipped it right in without trouble.
if it doesn't work after several tries, i've turned the engine off, then put it into gear and then turn it back on holding the clutch. we wonder if the throwout lever is going back far enough, but if it were not so, then i would think we'd be 'rabbit hop' starting as soon as i turn the key.
could the problems be related to just a sticky transmission - after all, the car hasn't been driven for more than a decade?