Seejay there are a couple of downloads on the 727 available such as
GA727 AOM.pdf which was put out by Flight 1 software for the 2004 another company 727. The best source on the net for how to fly the 727 was a site run by a chap called Benson but sadly the website is now defunct. I downloaded most of his stuff but lost the electronic copies with a recent hard drive failure. Anyway from the hardcopy here is the simple rule for calculating EPR's"

TWICE the altitude (FL)+1/2 the gross weight over 100,000=Last two digits of cruise EPR

Example: 140,000 lbs at Fl330
2 x 33=66 plus
(40/2=20)
=1.86 your cruise EPR

Simple once you get used to it. Sorry do not have a take-off EPR only worry about N1 and Temp limits staying out the red and yellow for a min or two as required.

Hope this helps

Make sure to search the forums for that great 727 FDE modification from Michael2.
There should be a link included to some very useful tables and you can fly them by the numbers with that mod (and gauge) installed.