[stagewex]

I am only 7 months into ownership of my 2002 Boxster but no stranger to older cars and motorcycles. I spent a long, long time looking for one specific to having history but also one with the IMS upgrade service done already. At 131,000 miles used but with one original owner and a 2nd that knew that original owner personally I found what I was looking for. All the box's were checked when I received a booklet of dealer service receipts from day one purchase. I'd rather have a car like this with history rather than one with few miles with no history and a bunch of owners.
Under my ownership I had the regular go-over by my nearby dealership who were able to track maintenance and only came up with one recommendation... the front tires while appearing new were of such an old date-code they recommended replacement. Kinda hard & getting brittle. Test ride after the swap confirmed improved handling and put away my research into new suspension. Rear tires were new just before purchase.

I'm just mentioning this because other than superficial and electronic upgrades I have not had to do much to this car thankfully. And I know from the service history when something has be changed or not so can follow a schedule per the owners service manuals all the time realizing this (in my case) is a 21 year old car that for all purposes was way ahead of it's time.
On a site like this there is a lot of technical help with things that are or have failed. That is always in the background as I suppose you realize with restorations of the vehicles you have listed in your stable.
Here's my kinda answer to you question... based on your experience with all those British cars that we lust after (I've had many MG's and Triumphs) but basically suck design-wise (why they all went out of business) I'd say a Boxster should be no problem for you. Parts if keeping as OEM as possible are expensive and servicing a mid-engine car might be a lot more involved than you Brit & American cars. But what you initially buy, a project or a driver will determine how much you are going to put into it time-wise & $$$.

I bought mine primarily for top-down use. It still has the 21 year old Vert top on it with a newer back plastic window. I should change it only for a better looking newer one but it holds the rain out so sticking with why I bought it in the first place, Rag Top. I do drive it in the Winter (now) and we have not had any snow at all here in the NYC Tri-State area at all. So weekends when it's too cold to ride a motorcycle and occasionally commuting to work in NYC.

You listed Mopar cars... extreme envy/so cool.
One thing I would caution is that at 6'2" and 175lbs. it is a very tight fit for me in the nice leather seats. I suppose they (the seats) may have adjusted to my body/frame with use and I have used leather conditioner on them every few weeks just to get them feeling supple again.
You listed a Firefab Jamaican? That's probably smaller and even harder to get into and out of. Figure I'm kinda describing something like that. I cannot drive this car with my wallet in my back pocket if you know what I mean. And these cars need to be driven, not just looked at.
Go find your Boxster but take your time looking. IMS and other upgrades should be at the top of your list. Or deduct what it will cost for you to do the work or a shop.

PS: I have installed the hardware to accept a hard-top though I do not have one. But if one comes up that is already my cars color-code and within 100-200 miles I'm ready to pick it up. Not a necessity but would be nice to have during the cold months. My Box is garaged year-round.