I've used these tubes in my SP10II for years. Clean/clear tone, neutral and very rugged. The latter is the principal reason I use them. Very rugged.
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Agreed for the most - they should be a fine match for the ARC. These Soviet-era military tubes are incredibly rugged and generally free of microphony, and are the tube of choice for units that are hard on tubes - the Audible Illusions springs readily to mind.
In some equipment, they can be a little too incisive, emphasizing the attack of notes a bit more than the body of the note. Tonally, they err a wee bit toward the lean and cool side. Tube rolling is a matter of matching tubes to equipment to emphasize the positive aspects of the gear, and ameliorate the negative aspects. It all comes down to one's own sonic priorities. Good listening.