Timing Chain is probably fine. Spring pressure is about zero and the motor doesn't rev above 5200. and if the chain breaks, put a new one on. It's not a miata.
Generally speaking I agree, except for this part.
The question isn't the strength of the chain, it is the nylon tipped gear that is the problem.
Buick v6 can, under circumstances have issues when if you jump time when running you run the risk of bending pushrods, having pistons hit valves, bending said valves, and running up the bill for head job and possibly replacing some pistons depending on damage. That said, on a 100% stock factory assembled engine, you should have plenty of clearance between piston/valve in a jump time situation to prevent damage unless the cam profile is way off stock, heads/block were decked/resurfaced, pistons changed things of that nature.
If you're going through stuff on a high dollar car I wouldn't cheap out on $150 in parts to go to an all steel gear and chain setup, especially with the proven issues those now 34 year old nylon teeth have with age.
If I had a 40k mile turbo car that's sat 20 years I wouldn't trust those things not to break off and have it jump time. (probably the biggest weak spot in the Buick v6 engine and arguably the largest reason for v6 powered gbodies getting junked or parted through the years.)
I wouldn't want to leave it on the side of the road broken down given how often they're stolen by snatch and grabs, and, I'd also want to keep it out of the hands of tow operators who are genreally careless.
However, your car, money, and risk, so go however you choose. May not break. If it does, you may get lucky or notnhave changed things and not do more damage. Or, you could get some mix of damage, or a car vandalized or stolen. All goes to your appetite for risk.
As far as mod selection, that I'd also generally agree with, but with one suggestion I left out the first post.
If the car is 100% stock, save every 100% stock piece - not just turbo, but uncut wastegate rod, chips, cat converter, even muffler.
Let's say you mod it and drive 25k miles. Given equal conditions it's worth more as a bone stock 65k model than it is a tastefully nodded one - caveat being you going out and putting a stage motor, repop gnx rear setup, etc etc and dropping insane money of course.