Sorry, the Mass Effect Series is not cross platform compatible.
The only thing you get to keep is your Galaxy At War percentage.
Re-gaining rank on the PC should be easier, as you know the system already.
Somebody else I saw in the forums doing the same thing tried to get some friends to help "Carry" them in higher level matches to get a lot more credits quicker. I think lots of Bronze and Silver matches until you find a friend is best.
While N7 500 does take awhile to get, many are a lot farther, so there is a lot of room to even pass your old rank.
