On an SB2 Handi frame, the 445 Supermag would be a better option than the 44mag, 300gr at ~2000fps is doable in the Supermag and doesn't require an expensive rebore, the chamber can be hand reamed with a rented reamer, the hardest part would be waiting for Starline to make brass!  

 The 265gr FTX would be a prime candidate IMO.
Tim
http://stevespages.com/page8d.htmhttp://www.hornady.com/store/44-Cal-.430-265-gr-FTX-for-444-Marlin/Trajectory for Custom .430 Hornady 265gr FTX at 2100 Feet per Second 
At an Elevation Angle of: 0 degrees
Ballistic Coefficients of: 0.225   0.225   0.225   0.225   0.225
Velocity Boundaries (Feet per Second) of: 2100   2100   2100   2100
Wind Direction is: 0.0 o'clock and a Wind Velocity of: 0.0 Miles per hour
Wind Components are (Miles per Hour): DownRange: 0.0   Cross Range: 0.0   Vertical: 0.0
Altitude: 0 Feet   Humidity: 70 Percent   Pressure: 29.53 in/Hg
Temperature: 59 F
Data Printed in English Units 
Range   Velocity   Energy   Momentum   Drop   Bullet Path   Wind Drift   Time of Flight
(Yards)   (Ft/Sec)   (Ft/Lbs)   (Lb-Sec)   (inches)   (inches)   (inches)   (Seconds)
0   2100.0   2594.5   2.47   -0.18   1.13   23430.58   0.000000000
50   1929.0   2189.2   2.27   -1.04   2.86   0.0   0.074531190
100   1767.1   1837.2   2.08   -4.43   4.88   0.0   0.155783768
150   1615.6   1535.5   1.90   -10.6   4.11   0.0   0.244579356
200   1475.8   1281.4   1.74   -20.11   0.0   0.0   0.341757629
250   1350.0   1072.2   1.59   -33.62   -8.11   0.0   0.448088003
300   1240.3   905.1   1.46   -51.91   -20.99   0.0   0.564111556