I ran safaris using a Canon EOS20D, and a clutch of what are now "L" lenses and not "L II", e.g. "EF 24-70mm f/2.8L USM" and "EF 70-200mm f/2.8L IS USM". Had to quit, but kept all my gear. Clearly, i need to ease into a more advanced camera body. The Canon Mark 5D III model seems along what I'd eventually like to get back to, and would be something that seems to be one I could hold onto as a second body hopefully. I'm curious if the first edition Canon L lenses are going to hold up, quality-wise. I was familiar with the limits of the IS in the L zoom models when I was using them. I don't mind upgrading way in the future, but assuming that my eventual goal would be along the lines of what's speculated about the potential release of a Canon 5D V later this year, do 1st edition Canon L IS lenses seem reasonable to work with for a while?
Those L lenses age very well. Meaning, there is almost no reason to quickly upgrade to the newer models. It is very reasonable to keep your "old" lenses. Yes, the IS is better now but that's really small differences in really high end products.
So I'd start with getting a current body and start shooting. The "old" lenses won't hinder you in any way. IF you think you are resticted by the lenses, you can still upgrade at a later time.
Since you've set down photography and are revisiting it now, it's my guess that the question is less about the camera, but how you'll feel getting back into it, and what the activity will mean for you/how you'll use it. (If you know this, sharing would help the recommendation.) For that reason, I'd suggest the best value-buy in the ballpark of your skill.
The Canon 6D has been very good to me, as an 'entry level' full frame that should be more than sufficient to get you warmed back up. I picked up a 6D Mark ii refurbished (by Canon) for $800 a few months ago.
Then, once you've got a camera in hand that you're not afraid to use (it takes less to justify going out for pictures with a $3000 body vs $800, in my opinion), you can start to answer the more personal question about which technology is worth my money, these days.