[jittsl]

I have both a 911 coupe and a 912 targa. If I want to travel quickly and enjoy the driving I take a coupe. If I want to cruise and enjoy the Texas spring I take the Targa. I love the open air. If I could only have one (and I could keep my race car for when I really want to enjoy rapid driving) I would probably have a 911 targa. As a PS, I have a factory '75 hardtop on my 69 (covered in vinyl to look like a soft top) and I have zero squeaks.

If it were me I would decide what I wanted and then buy the appropriate car. Unless your car is a junker to start with you will almost certainly devalue it by bastardizing it. I also suspect that you will probably be less than satisfied with your result if this really is the car you are going to learn bodywork on. There are a lot of subtle (and some not so subtle) differences between a coupe and a targa and although it has been proven that it can be done it is going to be a big job.

Since you asked our opinion about values MY OPINION is - it will cost you a lot in both labor and cash and there is no way it will end up more valuable. Coupes currently demand slightly higher prices but bastards always fetch much lower prices - there is no comparison between a wide body conversion (that emulates a factory option) and a targa to coupe conversion which is one man's folly. Once again, just my opinion.