need a little help....

hello all i am about to take the 3sp out and put in a 4sp in my 73 duster slightly built 318 ( cam, 340/360 heads, 670 holly ). i am looking at getting a new flywheel and clutch when i do the swap. i have done some reading and the centerforce dual friction clutch is what i am going to go with. i have that part but i am looing at flywheels on summit and they range from 33lbs to 12.2lbs. i dont know what a stock one weighs and if i spend $30 more i can get a 13lb flywheel over the 29lb flywheel. im not doing any hardcore racing but i do like to take it to the strip and play with me friends in their imports. i do drive it a lot on the street so i dont want to do anything to stop me from doing that. all the info i have looked up are people with high hp and tq motors or big blocks that say they love the light weight but i cant find anyone with a slightly built 318.

so any help would be awesome guy