Supension Required upgrade for Duster '76 440 BB RB

Good evening to all you Mopar Lovers, I am new to this of classic cars and i am really loving it each part i buy for my Plymouth duster is like getting a new toy. this car is a gift my Grandpa let for me before he past away so it something i am doing for him.

I already have a 440 BB with Schumacher headers and brackets with a 727 transmission.

This car has factory front disk brakes and drum brakes back( i am sure most of you guys already know this because of the knowledge i see you have). I have read lots of treads and it just get me more confused with all the technical terms.

I want to know if you can help me to know what modifications do I require in suspension front and back, i read that disk brakes is a must but i don't know if factory is enough. I don't see it has springs.

In the rear i also read i will require a different rear end and that a good option is the 8 3/4 with a 3.73 but honestly this is completely put of my knowledge. I want this car for street performance and want it to run good in the high way.

Any suggestions will be accepted and applied.

thank you in advance

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