Racetech 'Cartridge Emulators' - Inventors of this clever product which greatly improves the action of the damper-rod-style forks we have on our old Laverdas. They separate compression and rebound damping functions and provide a distinction between high and low speed compression damping oil flow. An excellent and cost-effective improvement for your old bike, I have been running these in my RGA since the mid-90's. Various Australian agents.
YSS PD Valves - Copies of the above, online shop option. ~$175.
Cartridge Conversion - There are various options these days for suspension specialists who will remove all the internals of your forks and replace with cartridges from a modern bike. In Australia, one I have heard of is by Trooper Lu's Garage in Sydney (no affiliation), but there are numerous suspension specialists around these days.
Maxton GP20 Cartridge - Maxton have manufactured their own cartridges that can be fitted to just about any old Laverda forks (maybe not the 35mm), including clever hidden compression and rebound damping adjustment. At around 300-500UKP depending on options they are excellent value, but you do need to send your forks to them, so postage ends up a bit pricey.
IKON - Took over production of the old Koni 7610 twin shocks. New 7614 version has a somewhat nicer aluminium body but retains the fairly basic internal system of the 7610 shock. These shocks are pretty outdated by now, but still a good option if the price is right..
Gazi - A new Australian-based company making a range of twin shocks for older bikes. Although I have no direct experience of them, they seem to look very nice and are very reasonably priced at between $690 and $780 given the specifications.
YSS - Various options for Laverda at between $899 and $1299. Good reports from a couple of people I know running them.
Maxton - A small UK company making top-end suspension products for road and race applications. Their T260-C shocks are a beautifully made product. No compression damping adjustment but they are built to your exact machine's specs. Excellent value at around UKP400.
Wilbers - A manufacturer of proper high-end suspension. They have a local distributor and listings for Laverda models, various options ranging from $1383 to $1950. Not cheap but you're getting a truly high-end product here.