Using lines from Synthetic to Dirt or Dirt to Synthetic

[Latekick]

One issue i find i have, often when Hollywood Park first opens after the Santa Anita meet, and also the Arlington meet after hawthorne, is that the times from a dirt and synthetic track are more often than not, Vastly different.
My question is, is it okay to rank horses based on their Synthetic race even if i am using dirt lines for some of the other horses. An advantage usually goes to the dirt lines for the Early parts and the dirt lines usually always "look" better.
Synthetic and Dirt are two completley different surfaces. Can i get your opinion on pace lines going from dirt to Synthetic or Synthetic to dirt