The first model year of the Mustang was 1964 1/2. It was introduced mid model year. The 1st year was available in only five colors, black, white, yellow, poppy orange/red, and a metalic turqoise/blue. There may have been a bright red also but I think that was introduced in 1965. The engine were a straight six, 260 and 289 V-8s. The interiors were also limited to black, white, red, and turqoise blue.
What kind of help do you need? There are many web sites dedicated to the Mustang and as much information as is necessary. Do a google search on the 64 1/2 Mustang and see if you can find what you need. If you do not find what you need I have an extensive library.