[uberman]

Please don't port the system or switch to a new source control system. I completely understand the temptation, but these are your best guess at priorities and almost certainly not your company's priorities.

Additionally if you switch to SVN to git you will likely drop all history. history that might be tied to an issue tracking system, even if that is an informal one.

In my opinion, your best first move will be to document the code as you work through it.