I think the biggest steel wheel on the 7/9xx range was 15" - no 16s steelies as far as i'm aware.
However, this may help somewhat :
https://www.carlsalter.com/wheel_fitments.html
I'm guessing you're going for the steel look to keep the original outward appearance of the 142 wheels? If memory serves the originals on them were 4.5J x 15 with 165 SR15 tyres, same as the rest of the 140 range.
You might be better looking at the 240 range for larger steel wheels but that fitment guide, althogh for alloys, will give you a few clues what other cars have the right PCD, offset and so on.
I believe Jag XJ6/12 Series I, II and III models with steelies might be an option, perhaps with hubcentric spacers to accomodate the different PCD while giving you a wider steel wheel.
Have you got a build thread for your 142?