Most up-to-date 48 emulator code (for command line)

[Orome]

I'm trying to locate the latest and greatest emulator code to build an RPL command line for (current) macOS. My naive approach is to just locate the current m48 code, cut the UI stuff, and wrap what's left for use interactively in Terminal. In theory that ought to be pretty simple, but I've got two problems:

1. it's hard to determine what instance of the code is "best", and
2. the code I have found is undocumented, especially with respect to sorting out how to pull out the RPL engine.

So I'd appreciate any opinions or thoughts about 1, especially if they lead to a version that solves 2.