I really like F McCauly's coach, I'm not near MT. My question in particuler is I'm worrying about 140.00 miles.Should I be?

Is that 140 miles? Many of us have routinely drive our motorhomes much farther than that. I went from our home in IL to upstate NY to buy our first motorhome, around 330 miles each way. Of course that was after months of research on RV ownership, and several hours of phone calls with the seller so I knew everything in advance that I possibly could know about this rig. Knowing what to expect is key.

I think he is concerned that the coach has over 140,000 miles on it.

(I think he means the 140,000 miles on the coach.)

This could indeed be cause for concern. This is not unheard of for the 454 but on the high side. Bears looking into. There may have been a rebuild along the way. If not, inspect well. Compression test would be #1 then check for oil leaks/consumption. With good oil pressure and history of good maintenance it could be fine.

Ah ok. Periods and commas get me confused.

140,000 could be a lot of miles on a gas coach, it all depends on maintenance and condition. See my comments above about doing plenty of research, communicating with the seller, and knowing exactly what you are getting before you get it.

Check out Jim&Tere's '85 28'

Re-power is not that expensive and rebuilding is cheaper. If you're concerned after a compression test and long drive have it rebuilt. BBCs run forever drinking a quart of oil a day. Fuel consumption is limited by the size of the line to the carb, 5/16" and down is 8 mpg. Re-power with newer technology and you may touch 10 mpg with a higher top end.
What you want is comfort and the layout you desire. Figure power is a variable not a constant. It is easier to change engines than layout.