They would have their work cut out for them, that I can see. They could reuse the .moarvm bytecode and file format, the NQP compiler and Moar backend [0]. I think many of the test cases are even common between the three backends... So all that's left to re-implement is a bytecode interpreter, IO facilities and FFI. That is, if my understanding of MoarVM is accurate.

[0] (https://github.com/perl6/nqp/tree/master/src/vm)