Use "cowboy" load data for the 44 mag. There is plenty of data out there to get the velocity as low as you want. Here is just a few to get you started.
http://data.hodgdon.com/cartridge_load.asp
200 GR. LRNFP CAST Hodgdon Universal .430" 1.570" 6.8gr 897fps 10,500 CUP 7.8gr 1045fps 15,400 CUP
200 GR. LRNFP CAST Winchester 231 .430" 1.570" 5.8 875 10,800 CUP 7.4 1039 16,700 CUP
200 GR. LRNFP CAST Hodgdon HP-38 .430" 1.570" 5.8 875 10,800 CUP 7.4 1039 16,700 CUP
200 GR. LRNFP CAST IMR SR 7625 .430" 1.570" 5.9 812 11,100 CUP
200 GR. LRNFP CAST IMR PB .430" 1.570" 5.1 781 10,700 CUP
200 GR. LRNFP CAST IMR Trail Boss .430" 1.570" 6.1 890 17,900 PSI 7.7 988 20,700 PSI
Jimbo