Help me choose a lowering kit

[Paul V]

As per title i need a bit of help choosing a lowering kit for my 1971 C10

1st one is ECE 4-6 kit
4/6 Drop Kits (2.5" Drop Spindles, 1.5" Drop Front Coil Springs, 6" Rear Drop Coil Springs, 4 KYB Shock Absorbers, Super Track Bar Kit, Shock Mount Relocator Kit) (Drop Spindles require Disc Brakes)
Cost $799

Looks like a good kit and i know it is recommended on here ( looking at the searches) but there is no mention of a C notch on the rear.

2nd one is Brothers 63-72 "ultimate" Suspension Kit - Drop Spindles

This is it! If you want the ultimate ride, stance and handling from your classic, you want this kit! All of these items have been tested, both separately and as a complete package in a number of BROTHERS projects but most noteably on our Project 1971 Suburban. In this Ultimate Kit you get drop-spindles, a complete set of lowered springs, sport shocks and anti-sway bars. In the rear, we've included our custom lowering springs, 1-1/2" lowering blocks with U-bolts, bolt-in C-notch kit, shocks, and an anti-sway bar. This combination retains full suspension travel by the use of the C-notch kit in the rear and the drop spindles in the front.
Cost $1379

It does not state how low it is on there site but i just called them and they say it is 4 1/2 on the front and 5 1/2 on the rear, confusing as it comes with a C-notch for the rear but it is not lower than the ECE 5 1/2 V 6"

The brother kit does come with front and rear sway bars which i think is why the kit is more money.

So any input guys Or recommend another kit