I'm not sure what the deal is with 1.7" long .30s - I just haven't looked into them. I can't really comment on the manufacturing issues making a jacketed bullet that long either. I just don't have the experience.
What I can say is there was a lot of work done by the BRL and other agencies - both here and by our allies that resulted in some pretty pragmatic software that can figure these problems out. McCoy's McDrag is a good one that gives reasonably accurate results. Most people know it as the BASIC program that you can download from JBM. It's cumbersome to use - you have to manually type in parameters and read the output. What I did was take the math behind it and re-write the software in a modern language so that I can iterate over thousands of combinations of parameters - different ogive lengths, meplat diameters, Rt/R values, boattail anlges, boattail lengths. This gets to a pretty good idea of what the maximum attainable BCs are. There is some judgement required (mainly the minimum bearing surface you're willing to tolerate and manufacturing limitations on meplat diameter), but one you settle on those, you can iterate over quite a few designs and get an idea of which ones are near optimal.
There's also a program he wrote called Intlift, which was based off a program written by Morris and adapted to small arms by McCoy. Between McDrag and Intlift, you can get a pretty good prediction of the aerodynamic coefficients required to calculate drag, stability, and a factor that I call "jump sensitivity" simply because I'm not sure if it has a proper name. I first ran across it in a study done by Bob McCoy on the accuracy of 5.56mm ammunition. It's not terribly clever, but it was one of those "why didn't I think of that" type of things.
In any case, it's a number not unlike BC that gives you an indication of a bullet's accuracy potential and is dependent on basically the same factors as stability. The difference is that you want a low jump sensitivity, not a high one. Jump sensitivity does not paint the entire picture of a bullet's accuracy however. It's just the bullet's sensitivity to aerodynamic jump induced by tipping at launch, which is one of the larger factors in overall accurac. It does not account for how easy it is to make a bullet fly without an initial yaw, for example. (You could make very low jump sensitivity bullet that is very inaccurate by reducing the bearing surface to zero, for example). But I've found that it's a pretty good indicator for reasonably designed bullets, and I've gotten a good correlation between group size and jump sensitivity by varying core weight in my 180s, for example.
That's where things get tricky and require some judgement. If you increase BC, you increase jump sensitivity, and neither is necessarily a linear change (with whatever factor you're considering). So at some point you have to choose a design that balances out the drag characteristics with the inherent accuracy potential of a bullet given the spin it's going to require (and the spin rates that are available for purchase - it does no good to design a bullet that's ideal for an 10.7 twist). If memory serves, a bullet made with a 1.4 inch jacket (so, about 1.440" long, give or take), maxes out BC at *roughly* .330ish. (Don't quote me on that - I'm going off memory here). But that is far from the most accurate bullet you can make of the same length jacket.
And none of this even touches the reality of what it would take to launch a 1.7" thirty at a reasonable velocity. So that's also a consideration. It could be that the long .224/2.43s get away with some things that .308s can't simply because they don't have to contend with the same recoil. Just speculating.
Edit: I would also be concerned about the bullet's structural integrity at 1.7". That's not only going to have a lot of spin, but it may require a fair amount of bearing surface and possibly a long barrel to take full advantage, which can lead to a lot of heat. I've never heard of a commercially available 1.7" jacket before, so who knows. I'm sure someone has tried it.