A 45-70 carbine has a greater range than a 44-40 rifle. But I agree with your overall point. But the percentage of Indians who had 1866 to 1873lever guns is not known. Perhaps some of the Indian crack shots had Sharps rifles which would have been more accurate at long range than the cavalry carbines.
My favorite account of the battle from an eyewitness is Chief Low Dog’s version.
Your worry about long range guns and short range guns is in vain. When hundreds of Indians are over running your troops right in your face, who cares what range the rifles are? Hell, shotguns would have worked.
I shoot a 45-70 rifle and the 44-40 is no match for it. The 45-70 is more like artillery than a rifle and is good out to very long distances (1,000 yards). The most likely round that Custers men were shooting was a 405 grain bullet with 55 grains of powder which was the load used for the Cavalry at the time as the heavier 500 grain bullet with 70 grains of powder was thought to have too much recoil for Cavalry units. Still 55 grain load would have been devastating at any distance.
The 44-40 is nothing more than a pistol round and is definitely short range.
The Trap Door Springfield was an excellant rifle and although the the Bureau of Indian affairs handed out repeaters to the indians in trade for goods, the repeaters did not seem to give the indians any real advantage. The Trapdoor was finally replaced by the Krag (.30 caliber)in about 1886 or so.