i have a 1970 buick 455 out of a station wagon .it is set up for an automatic trans. i would like to put a 4 speed manual trans in. do i have to do more than change the flex plate to a flywheel ?  

Depending on what trans you use. You will need to find a BOP bell housing for the trans to bolt to. Then you need to get the pedal assembly and linkage to the bell housing. I will have one available in a couple of weeks as I am pulling the 300 buick out of my vega. Only catch is it is a cable operated clutch. Let me know if it will work for you.