You can live without the built-in meter. You want a VF with thicker, brighter viewfinder framelines. You want a brass-top plate, but unlike the M3, M2 or M4, a camera which you can use with a motordrive or rapidwinder. So in other words, you're thinking of getting an older-model M4-P as a cheap and robust alternative to the MP!
Here is some background info about this particular model by Tom Abrahamsson:
The Leica logo on the M4P was stamped in on the brass top-plate version and in the later zinc-die cast top plate it was cast into the top at the casting stage. It is easy to figure out if your M4P has a brass or zinc top-plate. If the rangefinder windows (the small one and the light gathering one and the viewfinder window) are flush with the edge of the housing, it is a zinc top-plate. If the windows are recessed into the top-plate it has the brass top-plate. The switch over was made at around # 1610 000, although I have seen zinc top plates on cameras as early as # 1580 000 and brass one's on cameras as late as 1620 000.
The M4P has its serial number engraved on the accessory shoe and the top plates can be changed around. The # 1580 000 was most likely one that had its top plate replaced at some time and the late numbered one could have been one put together from parts.
The latest version of the M4P, from around 1650 000 had only one synch out let on the back. I have only seen this version with the zinc top plate. Mine is 1650 xxx (no snobbery, only that the camera at my workshop and I am not)! and it is a M4-P3, it has a M3 finder installed in it. Great camera and it has survived 8 month of being used as a testbench for Rapidwinders as well as being a good user. It probably goes through the equivalent of 30-40 rolls of film every day, week in week out and it is still working fine. The M4P is a very rugged camera and apart from some specials seems to resist 'collectible" status and hence is still reasonably priced.
For a while I owned a very early serial # M4-P (#1543xxx), and can report that after a shutter curtain replacement and full CLA, it was as tough as a tank. I used it every week with either compact M-Motor, rapidwinder or standard baseplate, and although the camera was already 20 years old, it will be good for at least another 20 years of hard, real-world usage (go tell that to the EOS crowd).
BTW, you can read the M4-P manual online at the following URL:
Finally, see <Greenspun.com: #008hSZ> for a detailed April 2002 discussion on the Greenspun Leica Forum about the development, features and evolution of the M4-P.