"I've read that a few Arisaka sporters have been made in Finland using Arisakas obtained from the Russians at the end of WW1."

That's true. VALMET and some smaller custom shops converted those Arisaka-rifles for hunting. They used to make those rifleds to "wild cat" -kaliber 7x54 which was made by converting 6,5 swede case for 7 mm (.283) bullet.