If you do decide to modify it, you might want to move over to HiPo where we sppecifically focus on that kind of thing.
As far as "upgrades" to the suspension go, your options are really ro rebuild it stock with modern components or put some kind of IFS under it.
Given that you mentioned lowering, the Mustang II based system is probably your best bet. Several vendors sell a
bolt on crossmember to install one.
From the look of your shop, fabrication is likely within your skillset, so a weld-in setup might be preferable.
