Sota Sapphire arm help?

Hello everybody. So I ended up purchasing a Sota Sapphire on eBay. Came with a Sumiko Premier MMT tonearm. Well, as is turns out, the arm is no good. Rather than send the whole thing back, the seller has agreed to replace the tonearm. The Premiers are pretty tough to come by, so my question is this: How do you match a tonearm to a table that has an armboard for a specific arm? This turntable came with a premade armboard for the Premier, but I'm wondering if I can find a different arm (Rega RB250 or 300 perhaps?) that'd just be an easy swap without having to have a new armboard made. Any help is greatly appreciated. My first "real" turntable shows up & can't even use it yet. Bummer.

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