Originally Posted by Gnzo

TM, I am going to say GET THE 350! Now let me explain before I get reamed for suggesting you put a Chevy (sacrilege!) engine into your mustang. With your question, you just compared the name of a car with the engine of a car. A 65-67 Ford mustang GT350, which I assume you mean by "350" actually had a 289 small block V8. Also offered in '67 was the 390 big-block V8. In '67 Ford made the mustang 2 in wider and 2 in longer. Now able to hold a big-block, the 390 was Ford's answer to the Camaro SS 396 (although the 390 couldn't match the Camaro's horses). The race-bread 427 wasn't offered until 1968 and was actually only offered for a limited time because of the cost involved in making it and maintaining it was so high. Ford replaced the 427 with a 428 later that year. The 428 dyno'ed at just over 400hp which was more than the Camaro could put out. Because of this, the 427 is harder and more expensive to get. Also in '68, Ford released the 302, a stroked version of the classic 289. (Note: The 428 was actually offered in '67 from Shelby as the GT500, but not from Ford)

So your question should be, 289, 390, or 428? The answer is 289. Most Mustang experts will tell you that although the 428 is an amazing engine, it makes the mustang extremely nose heavy and its handling ability falls far short of the 289. The 390 shouldn't even be considered. Only slightly lighter than the 427, and 428, it doesn't put out anywhere close to the horse power that its big brothers do. The 289 is a very common engine; parts are easy to find, and since the engine won't match the vin anyway, having it bored 30 over is an easy way to improve its performance. You can easily get that engine to put out 300hp on the dyno with some very common modifications.

TM, you have purchased my favorite mustang, or almost favorite. I love the 67 GT Convertible. It is a really fun car that should bring you years of enjoyment! I hope you enjoy it!