Many loading manuals, some thirty years old to more modern publications, will be all over the board. Some disparities have to do with how pressures were measured then with how pressures are measured today. Measuring the crush on a copper pellet compared to the more modern method of using a piezo transducer is why older manuals may be higher in pressure numbers than modern ones. Powder development and formulation of new ones have also changed many recipes. The single thing to remember is the safe load pressure your rifle (lever action Marlin) is designed to handle and operate with safely. Make note of how to look for pressures signs too; hard extraction, brass flow, blown primers, flattened primers, etc.
The Marlin is designed to safely handle pressures up to 43.000 PSI. Use that as the rule of thumb for the utmost max. when you reload and you should be fine. There is no need to go there though, for your shoulder will give out long before the gun does. Just make note that some load manuals list PSI, while others use CUP (copper units of pressure.) If you look at the Hodgdon .45-70 Govt. load data for lever actions that's online, most loads don't exceed 38,000-psi or 40,000 CUP.
