Will this help?
Kawasaki Brake Disc Sizes
BRAKE DISC ROTORS:
Brake disc: KD1
FRONT Z250A3 Z400J12/J3 Z440D/H Z550A2/A3 Z550C1/C2(LTD) Z550D1(GPZ) Z650F2/F3/F4 Z750R1(GPZ) Z750E/L/H GT750-SHAFT VN750A
Brake disc: KD2
FRONT EN450A EN500A/B GT550G-SHAFT Z1000J1/J2 Z1000K1/K2 GPZ1100B1 Z1100A1/A2/A3-SHAFT
Brake disc: KD3
FRONT Z1000J3 Z1000R2 GPZ1100B2
Brake disc: KD4
FRONT GPZ500S ER-5 ZX750G (GPZ750R) ZX750E1/E2 (TURBO) GPZ900R-A1-A6 GPZ1000RX ZL100A-ELIMINATOR ZX1100A1/A3 (GPZ)
Brake disc: KD5
FRONT ZX400C2 GPZ600R ZX750A1-A5(GPZ) GTR1000 A1-A7
Brake disc: KD6
FRONT KR1-S ZZR250 ZXR400H ZR550B-ZEPHYR ZL600B-ELIMINATOR ZX6R-F1-F4 ZZR600D/E ZR750C/D-ZEPHYR GPZ900R A7-A11 GTR1000 A9-A14 GPZ1100E/F
Brake disc: KD7
FRONT ZXR750H1/H2 ZR1100A/B-ZEPHYR ZRX1100C ZZR1100C1-C3
Brake disc: KD17
FRONT ZXR750J1/J2 K1 L1/L2/L3 M1/M2 ZX7-R P1/P2/P3/P4/P5/P6 ZX7-RR N1 ZX9R-B1/B2/B3 ZZR1100D1-D7
Brake disc: KD8
FRONT ZX10-ZX1000B 1988-1991
Brake disc: KD9
REAR ZX400C2 ZX550A1-A5(GPZ) ZX750A1-A5(GPZ) GPZ1000RX
Brake disc: KD10
REAR Z550D1 (GPZ) Z750R1 (GPZ) GT750P-SHAFT Z750E/H/L
Brake disc: KD11
REAR Z1000J1/J2/J3 Z1000K1/K2 Z1000R2 GPZ1100B1/B2 Z1100A1/A2/A3-SHAFT VN1500B2
Brake disc: KD12
REAR GPZ600R GPZ900R A7-A11 ZX10 B1-B3 ZZR1100C1-C3
Brake disc: KD13
REAR ZXR400H ZX-4 ZXR400L ZR550B-ZEPHYR ZZR600E GPX750R ZR750C/D ZEPHYR
Brake disc: KD14
REAR ZXR750H/J/K/L/M ZX7-R P1-P6 ZX7RR-N1 ZX9-R B1-B4
Brake disc: KD15
REAR ZZR1100D1-D7
Brake disc: KD16
REAR ZX750G (GPZ) ZX750E-TURBO GPZ900R A1-A6 ZL1000A-ELIMINATOR ZX1100A1/A2/A3 (GPZ)
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Kawasaki Brake Disc Measurements
Z1100A1-A3 shaft. Front disc =236 mm, rear disc= 236 mm.
GPz B1 twin shock model. Front disc = 236 mm, rear disc = 236 mm
GPz B2 twin shock model. Front disc = 246 mm, rear disc = 236 mm
Z1000J. Front disc =236 mm, rear disc =236 mm
GPz 1100A1-3. Front disc =246 mm, rear disc =236 mm.
However, the unitrack discs look different in design/style to the B2 ones. Worth a closer look to see if the mountings are the same though.