Howdy 1858REM
First off I think that the price tag on that rifle is pretty decent if you like the rifle. Depending on which model the Nikon is it could classify as a very good deal. Secondly, I don't believe that 3x9 is enough scope for long distance varmints or target shooting. You could perhaps start out with it then trade or sell it off for something a bit stronger. You could also put it on another rifle that you don't expect to shoot at such long ranges. Next, the 204 is a very accurate cartridge and does very well in a lot of guns. It might not handle the 39s and 40s very well with the 12 twist. I am guessing that this is a sporter weight barrel, not a heavy V/T type barrel. If it is a sporter weight rifle, I doubt that it will shoot 3/4 MOA all the way out to 400, but it might. You just never know. As far as the 22-250 being a barrel burner is concerned, most people will never shoot a rifle enough to shoot out the barrel. Improper cleaning has probably ruined more barrels than shooting them has.
Now, I may be the biggest Savage fan on this site and that is saying something. I have 2 VLP's in 204, 2 BVSS's in 223, a BVSS in 22-250, a BVSS in 220 Swift, a BVSS in 25-06, a 9317BVTS in 17HMR and last but not least a brand new model 12 F-Class in 6mm BR. The first one I bought was a model 12 BVSS in 223 and I honestly thought that it couldn't get any better than that. In no time I had hand-loads shooting sub half MOA. with a little more experimenting I had it down to normaly under 3/8" with lots of groups hovering around the 1/4" Mark. Then I bought my first 204 about 3 years ago, used. The dealer that sold me the rifle had one box of Hornady 32 grainers. When I took it to the range I used the first five for sighters then proceeded to shoot 3, 5 shot groups with it. ALL THREE went under 3/8" at 100 yards. If I do my part my handloads will do a little better with several sub 1/4" groups to my credit. The second 204 isn't quite that good but it will still shoot 1/2MOA or better most of the time. You can get a good deal on a used Savage quite often and generally speaking they are great shooters. Honestly though I think you could easily get your money back out of the Ruger should you buy it and not like it. You might even make a few bucks. Buy it, shoot it and, if you don't like it, sell it.