Thanks for your response SEAKphotog, and yes, this does help. Unfortunately, the final link of that thread (the one with photos), is a broken or invalid link, but the balance of that thread tells me that the reinstallation is in-fact problematic, and while it gives an array of possible suggestions, it appears clear that there is no uniform or singular way to get this done.
I'm going to be working with the firearm again today, so I'll try some of these suggestions, but it's important to note (or reiterate), that unlike the left side detent, once installed, the right side detent appears to be in a 'fixed' position, such that it protrudes out into the safety lever orifice and does not move.
Now, that said, I'm no gunsmith, but if I've got that part right, then that fact alone implies that the lever itself must be inserted first, followed by the detent. It also implies that nothing [not even the safety axle (or shaft) once installed], keeps that detent from falling out other than lateral pressure from the sear cage (or extractor). So I'll be trying that approach here today, with particular attention paid to the slot position on the side of the lever itself, and we'll see what happens.
But thanks again for your post. Its been helpful and I greatly appreciate it. 👍