If the Spurs really threw caution to the wind...
Starters
1 Parker
2 Ginobili
3 Jefferson
4 Duncan
5 Wallace
Bench
1 Hill
2 Mason
2/3 Bowen
3 Nocioni
4 Blair
4/5 Mahinmi
5 Nesterovic
IR
1/2 McClinton
2/3 Hairston
3/4 Gist
Sign Wallace using the MLE. Sign Nesterovic using the LLE. Deal Finley, Bonner, and Williams (and perhaps a pick) to Sacto for Nocioni. Sign Bowen.
I think this is one of the most versatile rosters the Spurs could put together. Nice mix of young and old, athleticism and guile, outside shooting and scoring, and rebounding. Obviously this would be a bit pricey. But it's a buyer's market. If the Spurs are ready to make one final push for a championship in the remainder of Duncan's career, the sooner, the better.