Re: 6.5 STW
You can save yourself a lot of heartache by just going with the 7STW. Readily available brass, data, dies etc.
You willl also save some barrel life which would not be too long in a 6.5STW.
On the other hand, the 6.5STW would be an interesting wildcat that few other shooters have. It should be quite capable of dropping anything from varmints to whitetails at about as far as you could hit them.