I'm 6'1" and 205# and don't have too much trouble (though I did add some head room to my car!) A lot depends on where you are tall but I would think that at 5'11", your height should not be a problem. I don't think your weight would be a problem in and of itself. A certain amount of flexibility is very helpful though but where there is a will to get into and out of a Europa, there is most likely a way - within certain parameters, of course. Sandyman reminds me that for some, the size of their feet is a limitation. I have 10 1/2 feet and I have to wear moccasins or driving shoes. I cannot wear most sneakers to drive. If you have size 13 EEE, you will have a hard time.
The A/C requirement is going to require a little more motivation. When TCs were new, there was a kit to add A/C. I'm sure that company is no longer in business and I think you're not likely to find one of those kits at all much less in usable condition. But learning about it does provide a path to follow. Then, with all the hot rods around, there are lots of places that sell small units you should be able to install in a Europa with a little imagination for where and how to put things. Unfortunately, a kit is very unlikely. Of course, this will probably make it a little bit of a pricey proposition. There are a few guys on this forum who have A/C in their Europa and might be able to offer some guidance. After that, a light color car with a light color cloth interior helps a lot. I know a little bit about the heat in Texas and I will admit that even with that, you would want to do as little driving in the summer and likely some of spring and fall!
As for desirability, everybody seems to have their favorite. I prefer the TC body but a lot of people like the cleaner lines of the S2 and then there are different S2 and S1 bodies that some prefer. With the right engine, an S2 could perform very close to a TC.
