On the timeline you're talking the GM is going to be much easier to keep on the road just due to sheer numbers.
Which would you rather rebuild in the current year, a dumb old flathead that someone cobbled a Powerglide onto the back of a or a vastly "superior" MEL backed by a MX transmission? Which would you rather source vehicle specific parts for, a POS tri-five or a same age Thunderbird?
Service information, repair parts and used parts are going to be a lot less available for that Toyota in 2035 than they will for the Chevy even if it's 20yr older.
The idiots can screech about ToyotaReliability all they want but at some point shit will wear out and will need major work and when that happens it's gonna be a much bigger PITA on both the sourcing parts front and on the sourcing information front than the Chevy. Or maybe not, the fact that you're even considering a Toyota means you're probably the kind of person who doesn't put much wear and tear on things.
Having a "classic burb" that's simply a "classic burb" and not some lower production niche vehicle that you don't have to stash parts for when you see them come up cheap is worth a lot.
If they're so good why are you on your third?
Or is this like German cars where you turn in your lease every few years and it's "good" because it didn't have major problems in 3/36?
5R110 was an option way earlier though, just not all had it.