It is allowable to the extent of dua only. However, add these words in your dua: “O Almighty Allah, if doing nikah is better for me with her then ? ? ? It should be noted that before marriage she is stranger for you, it is not lawful to talk to her rather it is necessary to observe purdah with her.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband