Spatial Join with two line data

I have two shape files from a vendor, one is two years and the other is very new one (same geography).  In the old one, i have added few columns and most of the rows are updated.

I wanted to replace the old one with the new one, i have to bring those added columns with values into this new one.  
Constraints:
a) The unique id given in the two data are not matching
b) the geometry is not matching,
c) Old line data is having 0.2 millions

I tried with spatial join (intersect, closest) in arcmap 9.3, but it end up with wrong joins or missed joins..

I have tried the following,
a) convert the new line feature into a point feature ( need arcinfo license),
b) create a buffer of the old data - line feature
        this buffer distance should be fine tuned, to cover the new line feature, mostly it will be manual decision
c) intersect these two data
d) now you will get the intersected points with the attributes from the old one.
e) do join this intersected file with the new one based on the unique id