Hello George! Your rifle is at stake here, so we referred your question to Sellier & Bellot themselves. Here is what they said:
"We have not tested the 4570GOVT in that rifle as it was produced for the more modern lever guns etc…
"We have it listed at 1500fps and most 45-70 loads will fall in the 1300fps range for safe use in the old Trapdoor rifles. If the firearm is in good condition and can be fired with other current production loads it would be prudent to stick to the lowest velocity or pressure rounds that you can find.
"The firearm might handle the load but overtime and repeated use it might be too much for the rifle.
"Sorry to be so vague but it will probably work but depends on the condition of the firearm."