There is a small hurdle to overcome in MiST. The MiST needs Quartus 13 to synthesize the cores, and instead both MiSTer and SiDi use the Quartus 17 versions. Our preferred manufacturer (manuferhi.com) will port to MiST. Actually I would love for the MiST port to be a success.
Remember that SiDi carries a Cyclone IV and the MiST a Cyclone III, yes, both have similar characteristics, memory, cells, but it is much easier to port to SiDi right now than to MiST.
Regarding the state of the core right now. You have to finish the Nick and start preparing the Dave. Later, depending on how the BUS can be implemented, it is necessary to think about either the disk controller or the SD-Card.
It shouldn't be a problem to equip the core with up to 4 MB of ram. Right now the audio upload works very well in ZXUNO but in MiSTer it is giving some problems due to the DAC converter.
We will keep you informed, thanks for all the support.