Yes, we've been making intercoolers for the 1978-89 Turbos:
TurboKraft : Catalog Home : 930 Thick Core Intercooler - $2,200.00
This flows a lot of air and supports more power than the CIS will support.
The Garretson unit is sometimes available through Andial, and you can sometimes have a "Longneck" version made (but have to add the 25mm port for the C2T diverter valve yourself).