Hello there,
I have vast C++ experience going back 25 years, working in R&D... in global names in electronics and software.,
Even though Power Basic is/was an interpreted language, 11.5 KLOC is quite a bit of code to convert to C++. SOmething worth bearing in mind, if one is to really undertake this, as a serious undertaking. :-)
May I ask, what this Power Basic code did on MS-DOS?