G-body instant center/9" brackets?

I'm working on putting a 9" under my Malibu, curious if someone can point me in the right direction. I have upper and lower brackets for the housing with multiple mounting holes, one set being stock location holes and I can go up or down from there.

Anyway, do I need to get the lower control arm parallel with the ground or frame? And mount the upper brackets so it gets the instant center close enough to be able to adjust with control arm length or hole placement? The lower arms have bushings on one end and heims on the other, bushing goes on chassis side correct? How much spacing needs to be allowed for between the heim and the bracket?

I have no engine/transmission in the car at the moment if that matters

Here are a few pics of what I'm working with

The chassis side upper brackets will be changed, it was built with bushed end control arms

Nobody?

The housing side? They were programmed long to give me some trim room, so I can fit them to the housing at the right height.

I retained the factory suspension style to still fit class rules, although the twin 70mm turbos I bought kinda threw that out the window. It's a forged 9:1 454, good 049 oval ports, mild hydraulic flat tappet cam, and the twin 70s, should make good power for a street car lol

I have a set of 315 drag radials for it, which are 31" tall