A very long time ago, there was a BASIC version of LabWindows. You could not convert a Rocky Mountain BASIC program directly, but it was a fairly simple fit. You could then translate that into C code automatically through LabWindows. That was one of its selling points; you didn't have to lose all of that old BASIC code. About 10 years ago, they decided to go with only a C version of LabWindows and renamed it LabWindows/CVI. This change was made because most people who were converting from BASIC to C already had and supporting two languages and a translator was very expensive (cost, memory, processing power, complexity, - expensive in every way).
If someone has an old version, you might have an upgrade path with your old code (no, I don't have any that old). Otherwise, you could build DLLs and call them with either LabVIEW or LabWindows/CVI. You could also recreate the code with the newer language.
Hope that this helps,
Bob Young