Is the Eibach part “Pro-Kit Lowering Springs 2804.140” the proper fit for a 91 Spirit R/T? And if it is, is $270 typical retail price? Thanks. Over all plan is Eibach Springs (4) KYB KG5563 Gas-a-Just Gas ShocksKYB GR-2 235902 Gas Suspension Strut Assembly. Just need it to be a "firm" daily driver for the time I am home. John.