To the OP - 1st of all to your issue about hitting small targets @ 300, 500, 700, 1000 etc...... I was where you are not terribly long ago. I had never really shot past 100 much. I thought 200 was LONG RANGE. But the limitation, I found out, was all mental. You don't need high end, $6000 AI rifles with $4000 Schmidt & Bender glass to shoot at 1k. You just need "decent" stuff and a willingness to learn and push yourself over that mental cliff. If you can shoot roughly MOA at 100 yds, you should be able to do that all the out to 1000. Nothing changes as the ranges get longer. The EXACT same technique is used at 100 as you would use at 1000. There is nothing magical about the distance. The gun doesn't know you are shooting at a particular distance. The gun will just do what you tell it to do. Garbage in, garbage out.
But this is where the "decent" equipment comes in. Yes, certainly there are going to be gear limits if you go too cheap or get something that is not designed for accuracy. For instance, a pencil barreled hunting rifle with a non-free floated stock, crappy weaver rings, an BSA scope, etc is not going to be very accurate. Especially as the barrel heats up from multiple rounds. But a decent rifle, with decent glass, decent base and rings, decent stock, better than decent ammo (match quality ammo) will get you consistently hitting the same man sized chest torso target @ 1000 that you were happy to just hit at 300.
As for glass - most everyone has chimed in on that. There are a lot of good scopes for under $1000. I second the Viper PST 6-24 FFP with the EBR-1 MRAD reticle. I don't have any personal experience with the others mentioned. But in general, I would make sure to get something with a "mil dot/hash" reticle of some sort. Fine crosshair reticles are ok for hunters and benchrest shooters. But a "tactical" reticle will make your life very easy for long range target shooting. There is just no reason not to get one. In fact I would say they are better for hunting than a duplex reticle. As some said - decide on your reticle choice (MOA or MIL) but whatever you do..... DO NOT get the mixed turrets and reticle. Make sure the scope is either all MOA or all MIL. Unless you are a masochist and just like when your brain hurts. I would personally suggest MIL, mainly because it is the US military standard and the world standard and MOA is slowly dying out. Mil scopes will be much more available and common. Don't get bogged down that MOA is close to inches and Mil is sometimes thought of as "metric system" (its not). Go read through the thread in the stupid marksmanship questions thread on the differences between MOA and mil. They both work exactly the same as long as you stop your brain from trying to then turn that measurement into a linear one like 3". Go read the thread, you'll understand what I mean.
As for stocks, there's too many good ones out there to list. Its kinda like scopes - it depends on your budget. If you want to not break the bank - probably THE best thing now is to look through the classifieds here and on similar forums for a Rem 700 "take-off" stock off something like a 5R, 700P or PSS. All it means it that someone is upgrading their stock and they have "taken off" their factory HS Precision stock. The HS Precisions are great stocks and they can be had very cheap. If you have the rubber Hogue stock, throw it away - its junk.
Finally, what Rem 700 do you have? I have never heard of a .308 with a 1:8 twist barrel. That almost sounds like a .223, but you said it was a .308 in the title.
Edit: Oh yeah, I forgot.... don't forget to budget in a good set of rings and a good base. No sense in spending $1000 on a scope just to put it in crappy rings. It is the link between your gun and the scope. Some of the lower end rings like Burris, SWFA, EGW will work ok. better though to spend a little bit more and get Seekins and you will be set for life.
Good luck!