Ok, so just to be clear: LR308 carbine buffer, LR308 carbine buffer spring, but a generic carbine buffer tube is OK, i.e. there is no carbine buffer tube that is large frame AR specific.
Ok...let's back up a minute. In direct response to your specific question quoted above...the DPMS LR-308 specific CAR buffer, LR-308 specific CAR buffer spring and ANY AR-15 collapsible receiver extension/buffer tube WILL work, but are NOT ideal and NOT the best you can do in terms of getting the most out of your setup. If you are on a tight budget, then those parts SHOULD fit and function just ok, but may cause you issues in the long run.
I would NOT, repeat NOT, use the standard LR-308 carbine buffer or spring on my own build. Frankly, the DPMS buffer is just too damn light in my experience with them. They weigh only ~3.5oz which is just slightly heavier than a standard 3.0oz AR-15 CAR buffer and only part-way to what an AR-15 H buffer weighs (4.0oz). That's not nearly enough weight for a buffer based on my experiences with generally overgassed .308 carbines (its the nature of the beast unless you have your barrel's gas port cut to a smaller diameter, OR you run an adjustable gas block to properly regulate the gas system). Similarly, the common .308 carbine buffer springs, while they WILL work ok, are not nearly as good as the springs offered by Slash in the link I gave you above and Slash's springs aren't much more expensive at only $15.
As for the buffer tube...there ARE some dedicated .308 carbine tubes. They are generally longer than the standard 7" tube to accommodate the longer AR-15 type carbine heavy buffers (AR-15 CAR buffer = ~3.25" long and AR-10 CAR "short" buffer = ~2.5" long) and the need for the longer .308 carrier to cycle properly. This is done, in one instance, by Armalite on their factory production .308 CARs, but I advise against in for the aforementioned reasons, in addition to the fact that the longer tubes, while they will allow you to mount AR-15 stock bodies like the CTR, they will not collapse all the way because of the addt'l tube length and may cause you issues. However, by going with a proper, shortened, heavier .308 buffer like those from Slash, you get to use any AR-15 type CAR stock, with the proper AR-15 carbine tube, and it will fit/function as if it were running on any other AR and will help to settle any overgassing issues, as well as provide better overall function of your setup.
Hope that explains everything out a bit better than my first post did. Sorry for any confusion.
