I have a 64 and it was my second project car ever (perpetual work-in-progress/daily driver). Very easy and fun cars to work on. You can put a small-block V8 in your car with very little trouble, the hardest part is coming up with a good-breathing exhaust that isn't big $$$, but it can be done. Several things need to be upgraded for better safety and reliability like the front brakes and rear axle but overall it is a pretty straightforward build with little to no cutting/welding/fabrication needed to make it work. Even waking up the slant will pay off, these cars are light and handle well and with a little more hp are great fun on the street! Good luck and ask plenty of questions and post plenty of pics as you go!
-Tim