That's the $64,000 question Bill there's no perfect lathe choice out there me.
Mori Seiki MS-850 (16x33) is a beast of a lathe but at 4,500 lbs I'm still waffling. I know where there's a MS-1250 for only $4,900 but dang its a monster.
Logan 6565 perhaps the best fit for me, a 1440 lathe but 2,000 lbs and has 10 inch wide ways so its beefier than your modern 1440 lathe. It does lack some more modern features and its quite a rare lathe that doesn't come up for sale very often.
At present I have crossed off my list any lathe made in China or Taiwan.
I put the same motor and a little stronger mount on my PM1440E-LB lathe. It solved all my cut quality problems and the motor runs much cooler than the original one did. The mounts I used were #9213K35 and are rated at 55 lbs shear. So far they are showing no signs of stress holding the motor up. I was lucky with the belt cover on mine. I added an extra 1/2 inch spacer between the lathe body and the motor mount so the motor wiring box would clear the drip pan. The belt clears the cover with no problems .
It's only been a few days but I'm very happy with the results. Thanks for posting this, it helped motivate me to solving my problems.
Necroposting this to say that I'm using the same 9213K35 mounts from Mcmaster on my G4003G that Badspeller/Mike is using. I'm also using the link belts from Horrible Freight. Definitely a smooth beast, she is now! It's been about 8 months and the mounts aren't drooping. Definitely worth the relatively small price $5.17/each and then cutting back some of the cover because it hits the belts with those mounts on the motor. Coolidge and Badspeller, how's your motor mounts holding up?
Not to take anything away from the above discussion, it is a valid solution for the problem.
My Atlas Clausing MK2 (some may think this is not a real lathe) had a surface finish problem, I felt it was transmission of vibration from the motor. (both motor and lathe are bolted to a wooden work top.) I installed thin plastic damping material between all mounting surfaces, this reduced the buzzing by (I'm guessing 60%) I still had finish chatter. While grasping at straws, I loosened the belt. Chatter disappeared. I've yet to slip the belt while cutting, but it will slip if I turn the lathe on with both high and back gear engaged.
That silly idler can aggravate headstock vibration issues on the MK2 I've noticed, the backward facing "wing" it's mounted on acts like a lever. I run mine a bit on the loose side too. But I also have a variable speed motor and don't run the spindle up very fast either.