I am looking for a rifle in .458 Lott. I am trying to decided between the Winchester Model 70 Safari in .458 Win which means it needs to be rechambered or the Ruger M77 Magnum which costs about $500 more. If it were your decision what would you go with and why?

The Winnie. Take 'some' of the money and bed it and clean up the feeding.

If you like the Ruger, I would go w/ that. For the money, it's quite a bargain. You would have to spend the price of the M70 again for better sights, 1/4 rib, banded front, etc. plus I think the Ruger's weight is closer to what I would want from a .458Lott.
Having said that, I am having my .404 made up on a M70. If Ruger had of followed thru w/ their original production in .404, I might have changed my mind.

if you want a lott in the m70 you should include the price of a barrel, because the action length is too short for a simple rechamber, you have to get the .375 and rebarrel it. the ruger is a damn nice gun but, my model70 in 458 win mag shoots in the .5-.4" range with 500 gr bullets. most of the rugers i've seen struggle to stay under 1.5", but they are nice, i'm considering one in .416 rigby.