H1B with otherthan GC sponsoring company

[luck2u]

Currently I'm with Company X till end of June'2012 and my PERM got cleared last week of June. Now I returned to India as my 6 years of H1B is completed and got PERM approval just one day before my last day of 6 years of H1B. Though I'm in India now, my employer (Company X) is applying for I-140 and then planning to apply for H1B extension with I-140. But after I-140 approval, can I apply for H1B with Company Y based on Company X's I-140 as Company X will not revoke my I-140 though my H1B is with someother company due to good relationship among us.

If any company (Company Y) comes forward to process H1B from India for me with existing I-140, can anyone tell me how critical would be the visa interview? I know visa interview is completely luck, just want to see did anyone came across this situation and attended for visa in any consulates located in India.

Thanks inadvance!!