I am thinking that, given its release, a port of Rastan would have been feasible. However, Taito could in no way half-ass it like they did with New Zealand Story, or make it cartoony like Cadash. It would need to be meaty and manly, like the game itself. Preferably with big booming bass tones to capture Rastan's epic soundtrack.
I think the PCE could have done it.
It will be an eternal mystery to me why it is the awful, terrible, total-garbage Rastan II that ended up being ported multiple times, with the superior first game left to languish on the Master System alone.