http://www.koni.com/car-racing/home/
Since Koni is based in the province of South Holland (Oud Beijerland, NL), I would suspect that you would have a distinct advantage in pricing if you are able to obtain Koni shocks for your Corvair from a local distributor or source in Holland.
Searching the Koni website for Chevrolet Corvair did not produce a result, so I don't know if these items for Corvair are a special production run or if you will have some difficulty with obtaining Koni shocks for Late Model Corvairs locally because the Corvair may not be included in their standard catalogs.
Here are the Koni shock absorber part numbers provided by Rick Loving on the Corvair Center website...
http://corvaircenter.com/phorum/read.ph ... 818,197663
1965-1969 Chevrolet Corvair
80 1739 (front)
80 1740 (rear)
The original REAL late model KONI numbers are
Front 80A-1739
Rear 80-1740
Here is another coil spring source that can provide Corvair springs, but they are also located in the USA...

I suspect this source could build Corvair springs that would be properly calibrated to produce desired support and body height. They would be familiar with spring design, so that correct materials and other parameters could be chosen to result in a safe design that would produce needed support, fitment, and ride height. Just click on "Request a Quote" and dial in the information about your car, including desired ride height adjustments and lowering...
Antique / Hot Rod Coil Springs
These symbols of yesterday can be found getting a new life for the road in garages all across the world. Although most are being restored to their original condition, many are after a specific look, such as the gasser look of the race track or the slow and low easy rider of Main Street. Whatever your goal, Coil Spring Specialties has the expertise to set your project vehicle at your desired height. And don't over look weight changes. These changes can significantly change the load dynamics and trim height of your vehicle. So if you gain or lose a few pounds due to engine swaps or chassis and body modifications, we can compensate for these changes with a new pair of springs.
Whatever the make or model, from classic collectibles to muscle cars, show-stopping originals to clones, we have supplied auto enthusiasts with coil springs, all 100% calibrated to fulfill their suspension needs.
We build each set of springs to your vehicle's specifications. We will need YEAR, MAKE, MODEL, ENGINE SIZE, TRANSMISSION TYPE, and A/C to put into account for each car we engineer for, as all these options play into the manufacturing of your springs
http://www.coilsprings.com/classic.aspx
Call (785) 437-2025