I have a 72' thats been repaired of all of its rust, and hell hole is repaired.

I wanted to know if i can swap absolutely everything between the two cars.

I have completely rebuilt suspension, Brakes, wheel bearings, suspension bushings, swaybars, using a lot of upgraded elephant racing, etc.... and new parts on the 74' but want to move them all over to the 72'.

The 72' Chassis in very good condition the 74' will require time and money.

The 74' has a 04' 40k mile 2.5L subie NA engine and a dr. evil side shifting trans.

Will the 74' side shift linkage work in the 72'?

As long as you swap all compatible pieces as a set. EG: side shifter linkages with the side shift tranny. Otherwise, If it fit on one chassis it should fit on another. Bumpers notwithstanding (early vs BUB), but not an issue for you

Oh... I forgot.

The firewall bushing will need to be a special adapter bushing, or I would suggest you use Tangerine racings firewall bushing solution..it's better in many ways.

You cannot mix and match front struts, brakes etc, those are all different.

Everything will bolt right in with the exception of that bushing.