回复：Sorry,you can't use old I-140 for I-485,because the

My understanding is that I-140 petition is based on future employment. If your old employer can keep that same job offer for you and you will come back to your old employer to work at that same position for a reasonable period of time after 485 approved, you should be able to use the old I-140.

This is critical for you so please consult a lawyer.