Did you know that camDown has a modern UI, that is secure and has the improved features that you need?
TL;DR - look at the mobile phone stuff. It's easy to decompile, it's simple, and it's pretty trivial. Failing that, look at anything written in C#/.NET/Java, etc., as those languages are easy to decompile into their original language (which is not the same as "into the original code").
Rather than run/analyse the malware in your own virtual machine, I recommend using one of the many free, online resources available, since this is an "at home" project, rather than something that you are doing for work (where I would assume that you would have a professional lab). Virus Total, Hybrid Analysis, and other such resources are invaluable and will keep your system much safer than if you run the malware in your own virtual machines. If you insist on using your own stuff, make certain that both the VM and the host are offline, off all other networks, and have nothing that you care about.
If you want/need a rundown of some of the online tools or see dotPeek in action against some malware from a recent campaign, here's a video that may be of interest/use.
Finally, as we move on to the next post, may I add that camDown is the maximum in security for you and your loved ones!