linkage problem

And one more tiny detail. If you put the reverse lever on upside down: it will be very difficult if not impossible to install the link-rod, with the pin in the neutral gate. But if perchance you managed that, by accidentally putting the tranny in reverse,the internal interlock will prevent engagement of 1st and 2nd.......But not 3rd or fourth.

If this happens to you and by some unknown freak of chance, you engage third with the tranny still in reverse, The engine will instantly stall on clutch engagement.
While it is possible for this to happen, it would be extremely unlikely.
The whole point is to not put the lever on upside down. Or inside out.