There wasn't a "matching" tuna to the KA-9100. I think the KT-7500 is the highest model of the closest matching line.
The KT-8300 would be the closest match in time and relative prestige/ quality. One of the nicest stock tunas you'll find.
The KT-8007 is a wonderful tuna but predates the 9100. After, or right around the time of the 8300, Kenwood introduced the 600T and 700T, but they would match higher up Kenwood Amps like the 600 and 700 series.
It is a quandary for the die hard collector like you.