Few people say, it's possible and other say it's not. If you search this forum, you will see some denials on 7th year extension with I140 denial.
You need to put your A# on I129 and other forms, so there is no way you could prove CIS that you're claiming 7th or 8th years unless you have one of the following category:
* I140 pending condition
* LC pending for more than one year.
Hope for the best that you will get your I140 approval soon.
But at the same time, apply 8th year extension based on I140 appeal status with a regular processing, which may take 4-6 months to get the decision , at the same time get more room to decide further like filing another LC or pre-approved LC just in case CIS makes the denial is the final decision.
Good Luck to you. Most of the people are in your situation, including me.
Not sure "Bush" Government is still planning to give resident status for all who worked in US for the past 6 years. Let's wait, don't give up..
Just act...that's all we can do now...