Power to manual brakes questions

hello I have a 1973 Plymouth duster.it has power disc brakes, drum rear for now .later I will be installing an 8.8 disc rearend.i want to run a newer aluminum master cylinder.so I know I need the 4 bolt to 2 bolt adapter.so what pushrod will I need since the adapter will add so I’m not sure if a manual rod will work do I have to buy an adjustable rod?or can I use my factory power brake one ?thought since the adapter is there it will work?im lost on this rite now.im on a budget so will be buying off of eBay.if all I need is pushrod who can sell me one ?thanks (I’m horrible at typing/texting I have carpal tunnel and bad nerve damage in my arms)