Four observations:
1. Lincoln has roughly three years of rebuilding and coaching congress through a difficult path.
2. The Lincoln legacy is probably half of what it is today...with serious negatives over the period after the war.
3. Since he had a strong relationship to the railroad folks....I suspect they would have gone on like gang-busters in growth after the war.
4. Lincoln pardons for various southern leaders? Very likely and could have been a major step forward for the rebuilding.
RE: your #3
The railroads did go gangbusters during reconstruction, replacing much of the preexisting (approx) 11,000 miles of track (of various gauge) and (by 1890) adding 19,000 additional miles of track. Of course it was all paid for by heavy taxes.