Hot water baseboard help

Looking to add baseboard to my finished basement previous owner had a wood stove in there but really not into burning wood. I already added another zone to my boiler just up in the air on which baseboard and how much. The basement room is 26x18 with 7 foot ceilings all three exterior walls are below grade. The other wall butts up to a garage and the other half to a laundry room with heat. The foundation is block with furring strips on it with r-3 insulation board then sheet rock. My original plan was to put 20 feet of slant fin 30 in but I’m doing the math and I don’t think that is enough my next though was using multi/pak 80. The reason I only say 20 feet is that would be the easiest with tearing walls and ceilings down. Please let me know your thoughts.