2" .25w DOM is a good size for lowers and with the 1.5" ID, allows for 1.5" OD 1.25" ID thread inserts for the 1.25" shank JJ's. 1.75" x .125w tube will work well for the uppers. As for the mounts, you'll want to address the axle end as well. The lower mounts hang way too low and the upper mounts will be too low. At that point, there's no reason to keep the track bar so triangulation in at least the uppers will be needed. Also, when going longer and putting the mounts where they need to be on the frame, you'll likely run into clearance issues with the tub (and uppers) and the frame (lowers), all dependent upon how long the arms are and where they're mounted of course. I'd suggest doing some good research on link suspension geometry and reading some build threads where this topic is covered.
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