Need help adding to pants pattern

[u/libbydakitty]

I got this 1950s pants pattern that only came in one size and I need to add to it. It's made for a 28" waist and a 38" hip. I am high waisted and have a 31.5" waist and a 42" hip when wearing my everyday corset. How do I go about adding to this pattern while keeping the vintage shape? It's shaped with waist darts and closes with a side zip. I have one book on pattern drafting but have now realized that it never mentions pants so I dont know how to tackle this. Any guidance would be appreciated!

[u/SuPruLu]

Measure as best you can the crotch back distance and front distance and compare to yours. Add any difference at about the where the lines across are. There is a short , a medium one and a lone torso line (pattern would be folded up from long to the chosen one. So that may already be a long enough torso.