Thank you for all your inputs. According to change wheel size down I don't quite understand what you mean? Most used front wheel dimensions on traditional 33-34 Highboys are still 15" isnt it?

My chassis is only at the planning stage so far. I'm just checking the possibilities. However, some data is decided:
Jaguar Rear axle which is already bought
16x9" rear wheels equipped with 295/50-16 rubber
7 1/2 or 7x16" front wheels with suitable rubber.
The wheels are bought.