I'm definitely interested in upgrading my seats to something with more firmness, lumbar, and other support areas.
HACK has installed newer GTO seats into his Impala, and they are very comfortable! They hug you on the sides, and keep you in that seated, forward position. I don't think there was any track modification for them to bolt in either.
Obviously it will be nicer to find some donor seats that are more readily available, but I haven't yet done any research on the whole subject to able to pick out a donor vehicle for parts.
Clear Image Tri-Ys & Hi-Flow cats >> 2.5" X-Pipe & Magnaflow Tri-Chambers, Mike Harris 4L60E, Circle-D 2,400 RPM TC, All MOOG FT End & Del-A-Lum bushed MOOG CTRL Arms, Eibach FT & New Stock HT rear springs. Hotchkis Sway Bars & End Links, RAISS, 3.73 Gears in Eaton carrier, Dynoshaft & CIA Loop, BMR Trailing Arms, Braided Brake Hoses, Taylor Spiro-Pro Wires, AutoMeter Water Temp & Oil PSI Gauges, Impala Console. ATE Blue Brake Fluid. Skip White distributor. 20's, Z28 Cluster, Corbeau GTS Seat