C-Notch and shocks needed? Adjustable tracking bar too?

[Cavscout]

Just installed a set of 4" drop coil springs in the rear of my 70 LWB, the shocks I bought from Amazon don't fit so I need advice on which shocks to buy, LMC has drop shocks for $50 each.

Do I really need to C-Notch the frame with a 4" drop? My truck has the auxiliary leaf springs and I'm thinking this will be enough?

Last question, tried to install an adjustable tracking bar after the drop springs and the bar seems to be about 2" too long, the axle seems to be aligned correctly, do I need the adjustable tracking arm?

Thanks