Converting an Adventure

I am quite interested in Sands of Doom adventure for DND5e but not so fond of the system. I believe I could do a nice conversion for Draw Steel but there is one aspect that stumps me. Sands has a 40 day clock while DS focus more on moving stuff when they stop do rest and rests are a whole day thing.

Would you say better to leave the 40 day as is and just make rest not take the whole day or change the 40 day into X rests? If so...how many? I am leaning more on the second but I have trouble thinking of a good amount.