You mention reliability and daily driver and air conditioning........
As much as I find a V8 Miata swap appealing as fun, 2 things about it conflicts with your stated desires. Although with enough money you could build the little Frankenstein toy into a reliable daily driver with AC. Lol
But I'm around a lot of Miatas and there are FEW NA and NB's that are still in that kind of working order. Most of which are really still nice because they are low mileage and well taken care of.
Step up to the NC and ND and it is effortless to find examples of a much more modern Miata with the creature comforts that make it a defendable daily driver with extreme reliability. And while "more power" is something I would never poopoo, since I have the disease myself, these newer Miatas with the 155-185HP motors are sitting in cars that barely weigh more than 2000lbs.
Driven with spirit, they are not in anyone's way!
By the way, I love Miatas! It's hard to find a car that has that balance of minimum weight possible, but with the amenities that the spoiled man won't live without. All packaged in a remarkably reliable and relatively inexpensive toy. The BEST thing about them to me is you can literally TOSS them into corners and playfully experience over/understeer at safe speeds. I'm a suspension and handling junkie way more than a 0-60 guy.
Oh, and did I mention you can drop the top in 1.5 seconds while sitting behind the wheel?
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