Here for everyone is Bob Ashlocks business contact. He has done more than just a few of these, and he understands them really well:
TACH-ADAPT
Another, or additional way to go is an aftermarket CDI box. You can get your Bosch CDI fixed, then save it for a rainy day while letting your aftermarket box do the work. I have used Mallory HiFire Pro 695 on quite a few cars. It is semiconductor based, as opposed to the passive component based Bosch CDI, so it is more reliable and less expensive. It is also about the same size as the Bosch CDI, so you can put it in the same spot. GM HEI and Bosch VR distributors work on the same principle, so you just follow the HEI instructions to hook it up.