Just bear in mind how the 70s will affect your gear ratios. I have 315-80s on my 142 and it revs at 1700 rpm at 90kms. Your lorry could be screaming at 90 with those tires.
Hi there, you have taken on a mammoth project, people who do this type of job for a living would take about 18 months to complete. However, I wish you all the best with it all, will follow your journey to the end, I started my driving career on a 141 and am a Scania man thru and thru. Cheers.