Hi,
I am a Senior VB developer based in Australia.
My specialty is upgrading VB3/4/5/6 applications. I generally upgrade them directly to VB.NET.
You can download a free version of VB.NET 2015 (Community Edition) to view and edit the new project i would create for you. I could possibly mail you a DVD containing the VS2015 setup files if your internet connection is too slow (It's several Gb).
I would recumbent going to .NET rather than VB6 as VB6 has only been guaranteed it will function on Microsoft operating Systems until 2020.
13Mb is a bit large for an email, what i normally recommend is to create a (free) DropBox account, and upload the file there. It will create a folder on your computer that you can copy the file(s) to, and it will slowly upload them in the background. It is intelligent enough to resume the upload if your internet connection is intermittent or you can't upload the entire 13Mb in one session.
I have VB4 installed, and VB6, VB.NET 2008 (which is the last version of .NET that can convert VB6 projects to .NET) and the latest version which is Visual Studio 2015. (VB.NET 2015).
I would only need the source files, not the EXE.
I do not develop for MAC so I am unable to make comment on that but I could investigate further if this was a requirement. VB.NET can be converted to C# which is a lot closer to the languages used on a MAC. (I am actually typing this response on my Macbook so i am familiar with OS X).
I look forward to hearing from you.
Caleb.