I want to buy a 1967-1969 mustang?
mustangspecs.com is a good reference to find out what all the options were w/ a mustang for almost any given year.
Also if you really want a 60's mustang.......START SAVING UP NOW!!!
Cause 60's mustang are going for a premium these days (even the junkers) You can expect to spend up to at least 8-10k minimum just finding/buying a car worth restoring....and then expect to put another 15-20k into it for a proper restoration.
Anyway I don't know what you mean by "into my head" but you need to keep researching,reading,and studying if you're at all serious about this. We can only do so much since there is a TON of info you need to know just to be able to buy a decent car (nevermind everything that goes into restoring one too)