JF -- You should be able to safely run 275-40-17 tires front and rear on 9"rims, such as the YearOne 17x9 Mopar rally rims.. as they have the correct offset to fit our cars... without any major concerns. And seek some 200 TW tires for that size.. choices are minimal from the different brands... 18s are where its at today for best selections.

Keep in mind that these shorter sidewall and diameter tires do change the ride comfort.. and watch out for potholes as the rims can more easily get damaged.

If you're not up to getting larger TBs, such as FF's 1.18 (and you wouldn't regret it... only wondering why you didn't get them sooner!), then get double-adjust shocks.. QA1 or Vikings.. or similar... double-adjustables.

Skip the exotic rear suspension that your thinking about... Hotchkis or FF rear leafs would suite your needs just fine.

Consider a larger rear sway bar beyond the typical .75"... look for or have made at least .875 or 1.0"... because your car is front-end heavy.

Have you re-positioned the battery into the trunk yet?... = about 1% weight transfer.