My dad bought a '71 Spider (1750) after his unfortunate experience with his '69 911T, having to redo the whole top-end. He got it used and (probably) lugged it too much. He really liked the Spider and I remember him telling me that Alfas had sodium-filled exhaust valves. My brother and I both wrecked the car and I still feel guilty about my part in that. I may have qualified for that "good tires, certainly not great tires" excuse, as the Alfa had Michelin MXVs (I think) instead of the more likable (and progressive) Pirelli CN36s. Anyway, those cars have a way of getting under your skin and forming a special bond, as they're so sweet mechanically.
Anyway, I don't know what years or what-not was involved, but the "flying buttress" seats are cool and desirable. I doubt it would solve your seating issue, but it would be interesting if you could sit in a GTV equipped with those seats. Maybe some Recaros would help, I dunno.
FS: Flying Buttress seats + rear seat - Alfa Romeo Bulletin Board & Forums
Back in day, Jon Norman was considered one of the best gurus in the bay area. Looks like he's still around. I'll never forget him saying to my brother, who had a beautiful black 2000 Spider with exhaust and cams that didn't have enough power "it just doesn't seem to be as athletic as it should be." The next step for my brother was a different fuel injection distributor (I think). Never got around to it.
https://www.linkedin.com/pub/jon-norman/30/3a7/a41
Does your car have the real Cromodora Daytonas? Looks like it. Like Fuchs for Italians...