Interesting sounding project, look forward to seeing it slowly come together. As for finding period looking tyres at reasonable cost, have you tried Camskill?
https://www.camskill.co.uk/m4b0s0p0/...yres_-_14_inch
They have 14" 80 series tyres in all sizes from 135 to 185, with the greatest choice (and vfm) to be found in the 175mm width.
If you step up to a 15" wheel, they do 80 aspect tyres from 125 to 185mm, and the 165/80/15 (largest choice in that wheel size) would quite possibly be a suitable tyre for your project in terms of looks and handling characteristics.
Anyway, keep us posted with progress.
