Structurally/safety wise it's fine. But those trucks did tend to rust out badly- I had a '76 2WD Blazer that was a Fred Flintstone special as in no floor boards on either
side, plus the doors and sills completely rusted through or missing (it was from PA). The PO had used a cut up yield sign to reinforce it enough that your feet didn't hit the road.
Passenger side front was due to the batteries leaking/venting through the years. This is seen on nearly all vehicles that were around before sealed batteries, and is the main reason VW bugs all seem to have rusted out floors under the rear seat where the battery was.
I agree w/those who say don't bother trying to fix it up. Don't let sentiment cloud your judgement. I'd sell it as-is to someone like you mentioned. If the 4WD/transfer case/etc. all work, it still has value IMHO