The .30/06 has a ceiling of about 50,000CUP SAAMI and 51,000 CIP (both copper crusher method), which is listed also, as 60,000PSI SAAMI and 59,000PSI CIP.

The .45/70 is listed in the same chart as 28,000 PSI SAAMI and 32,000CUP CIP(Euro). Their copper crusher listings are 28,000 CUP SAAMI and 29,000CUP CIP. Go to http://kwk.us/pressures.html and see for yourself. Bookmarking this site will come in handy. Also - read the text as it explains points of measurement by either system and why the numbers don't always 'Jive'.

The .45/70's ceiling is what the rifle mfg'r says it is, in this case 31,990 or whatever PSI - note, that with the .45/70, and many other straight sided cases, PSI and CUP are indentical or exceptionally close numbers, ie: equal - 30,000CUP is 30,000PSI. It is with the bottle necked rounds where they become quite different.

Also note that Speer's manual lists loads for the Lever guns which Hodgdon then states are OK for Trapdoor Springfields because Speer limits the lever gun pressures to 28,000CUP(ie: 28,000PSI) or less. It is interesting they don't agree, but then, what would be the fun of that?

Hornady lists lever gun pressures to over 40,000PSI/CUP, as-does Hodgdon, while they maintain 'WEAK' actioned .45/70s at 28,000CUP/PSI.
Even at low pressures of 28,000PSI- almost 2,000fps can be obtained with 350gr. bullets - no flies on those ballistics. Try a 405gr. RP at 1,800fps and see it stagger a moose or elk.