Yes there are GM large cap HEI distributors made for EFI. I beleive 1990 Corvette would be a lookup... Yup found it on RockAuto.
http://www.rockauto.com/catalog/moreinfo.php?pk=1393025

I wonder if ACCEL would give you Spark Latency Corrections numbers for their module? Probably not in the book the tech support person reads...