Ummm ... I think that a conversion requires a few more parts ...
The ZiL-157 is a 6x6 truck and the ZiL-164 is a 4x2.
Horizontal bars in the grille is for the ZiS-150 (the last production year the name was changed to ZiL, de-Stalinisation).
The ZiS-150 is also a 4x2.
The rounded fenders are needed for both ZiS-150 and ZiL-164. The ZiL-157 was based on the ZiL-164 so it probably reused most of the cabin except for the fenders which were probably changed due to off-road requirements and the 6x6 layout.
I hope that the conversion will include new front axle and a new rear suspension (single axle instead of double) ....
The suspension is also higher on the ZiL-157 (for obvious reasons) ..
/ Robin
German language wikipedia (use Google translate or just check the images)
ZiL-164
https://de.wikipedia.org/wiki/ZIL-164ZiS-150 / ZiL-150
https://de.wikipedia.org/wiki/ZIS-150 ZiL-157
https://de.wikipedia.org/wiki/ZIL-157 Note the "flat" fenders and cross-country wheels, singles and 6x6