1] there is no reason to spend a lot of $$ to lower the car , I would use a 1" torsion bar & adjust the bar down or use a drop spindle , the rear can be lowered with lowering blocks between the diff & springs
2] I like 4 wheel disc although the rear brakes do little , but the disc will dissapate heat better than drum do & will not fade with hard use
3] I agree that the front buckets can be made to work , I have not tried the rear & it would take some work to fit them
4] If you want to go to a Hemi I would use a new block for the build & have an engine built to spec not buy a prebuilt crate , you can mount it with Schumaker mounts to your existing K frame , you will need headers or manifolds for the Hemi , virtually everything else can be used from the 383 , you will need a different flex plate or flywheel with the 8 bolt hemi crank . I cam build a very strong 440/512" stroker for approx the cost of heads & rocker gear alone for the hemi though
5] Personally the dash pad I got from JD was garbage & have better luck with Ultimate rides product
6]you can fit gauges into the stock dash or there are full custom panels available or can be made to fit the existing dash
