Usually they have 1:14" twist in a 458 Win and 458 Lott. What happens if they use a twist of 1:18"?
Do that 1:18" twist that the rifle shot badly?

Is the Ruger No 1 a good choice to build a 458 Lott on?

Ruger is chambering the 458 Lott in a Ruger No. 1 so there is no need to build one from scratch. As for the twist rate, a slower twist is good for a higher velocity. It depends on the weight of the projectile and the load, I doubt if you will see much difference between the twists listed above. Good luck.