There's been so much good advice here already, and I don't really have much to add.... but that's never stopped me before.
In truth, I just read the thread about the forum being dead and all the reasons proposed as being responsible for its demise. I find I'm moved to participate, rather than skim.
So my $0.02, whittled down to a few words as I can, since I'm typing on my phone;
Forget the PPI. Your awareness (as illustrated by your list) is at a pretty high level. Depending on the individual mechanic, a PPI will either confirm what you already know or nitpick the car to its ever lasting death. Neither are useful.
Here's my take: unless you are prepared to do even something major as a DIY, you shouldn't be buying a >20 yr-old car. It sounds to me like you're up for it, and recognize the work you'll need to put into it. (Kudos)
Mechanical items are all relatively easy, and comparatively inexpensive. Paint and body on the other hand, tend to be more expensive, unless it's your specialty. So find a car that (mostly) looks the way you want it to. Minor work is fine. But you'd better love the color.
The only mechanical item on your list that gives me pause is the noise at start-up.
Here's what I would do: as 78F350 said, low cash offer. But include in negotiation that you'll leave a good faith deposit while you await the expedited results from Blackstone labs, for the analysis on the oil you're going to send them. That'll tell you if the problem is interior to the motor.
Otherwise, buy the car that largely LOOKS how you want it to.
I've bought 78 cars/ trucks in my day. From '34 chevy's to 2013 Maseratis to a 2008 and a 2016 Ferrari, including not a single PPI. Only really been disappointed once. Look each car over the best you can, then pull the trigger.
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