Just bought a '67 fastback which has the original 289 4v motor and 4-speed top loader. This is my first vintage Mustang. Hasn't even been shipped to me yet and I'm already thinking bigger motor. It'll be a weekend driver, not a show or race car, but I like to go fast :: Can't do the work myself and I was hoping for opinions on how to get the biggest bang for my buck? What would be the biggest bolt in replacement motor I could go with? Would it be cheaper to go with a bigger, rebuilt bolt in replacement motor or maybe do a bunch of mods to my original 289 (the 289 was supposedly rebuilt to stock 1k miles ago) Also worried about what the top loader can handle.