want to convert od. PLEASE HELP!!!

hello mopar enthusiast

i'm a new member to this site and have found it to be very helpful so far. now heres my dilema i'm working on my 74 duster, im converting it a V8 four speed car. i have a cast iron four speed overdrive for it, and i would like to put diffrent gear ratios in it and make it something more like the 70-74 gear ratios. i have read some articles that very briefly touch on this subject, but dont make it very clear. so if any can clue me in that would be great, and if so wheres a good source for the parts that i would need?

thank you
Author: admin