personally having owned and used the marlin, in 444 and 45/70 extensively for 2 decades,
and after swapping too the BROWNING BLR in calibers 358 and 450 marlin
after extensive personal testing
Id say the BLR in 358 win is the most versatile and the BLR in 450 marlin, is a better substitute for the 45/70,
both BLR carbines are both much better more precisely machined,, stronger actions that allow pointed bullets and both BLR's are more accurate options ,
and both the BLRs can generally be found for near $1000 or less
the 450 marlin is listed at 44 k max pressure the 45/70 listed at 28 k max
keep in mind the BLR is available in 6.5 credmoor and 308 win, 243, and used in 270, 30/06, 257 roberts are available
https://www.browning.com/products/fi...weight-81.html
http://www.lasc.us/SAAMIMaxPressure.htm
http://kwk.us/pressures.html