You can jury rig your own, using the pinout of the J2 connector on the KA630.

J2 Pinout:
1-3	grnd
4-5	CPU # (0 == Master, 1-3 == Auxiliary CPU #) - this sets a slave #
6	grnd
7-11	display register bits
10	battery backup voltage for TOY clock
11	4th display register bit (above should be 7-9 for bits 0-2)
12	grnd
13-14	boot and diagnostic code
15	halt enable
16	grnd
17-19	console baud rate
20	+5 Volts

There are pullup resistors on pins 4-5, 13-15 and 17-19.

Basically setting bits 4 and/or 5 results in a slave. J3 can be connected as
a serial console port, as follows:
J3 pin		RS232 pin #
3		2
7		7
8		3
2,9		frame grnd

This should give you what you need to make enough of one up to work.

Good luck with it, rick