It's not the roads, it's the drivers. Most cars in this country never see rural roads; the damage is caused by sloppy driving in towns. There's a speedbump outside my house that some drivers think they can go right over at 50km/h. Keep doing that every day, and you'll knacker your front shocks no matter how the road is surfaced.
On the OP, all the suspension bushes in Alfas are prone to wear, not just the front - putting in polyurethane bushes instead of the rubber ones will stop the wear, but your spine won't thank you if you're driving around West Cork.
I fitted Koni FSD shocks to my 147 years ago, and they helped the ride (it's firmer, but less bumpy), and I do think they've reduced the wear on the bushes and other suspension parts (90,000km and still on the original bushes). They're pricey, though, and I don't know if they'd be worth it on a second-hand car. If I were doing it again, I'd probably swap the springs too, but at the time I just couldn't find springs that wouldn't lower the car, or make the suspension stiffer again.
The big cost with the 156/147/GT is the front anti-roll bar, which is an absolute ***** to replace, requiring a disassembly of the front of the car. The part is only about €100, but there's three to four hours of labour in changing it. Sympton is a rattle from both sides when going over bumps. Upper wishbones are cheap enough to fix (about €150 each at a dealer, cheaper at an independent), lower ones less so. Wishbone problems manifest as a squeak over speedbumps and suchlike. Rear suspension is generally okay, but the bushes go there too.