Yes, yes, yes, the Dragunov owners are right, the PSL is NOT A DRAGUNOV.
Now that we have gotten that out of the way, (it really is obligatory for the Draggers to do this, please understand) let us discuss this.
The PSL, (okay, I have to oblige, too) to begin with, is a DMR just like the SVD. It fulfills the same role with the same reliability, comparable combat accuracy, and equal if not better optics (the Romanian glass is better, but the Russians do provide higher magnification scopes).
First, shortening the barrel can actually make it more accurate, because it reduces flex in the barrel at firing. In any case, this was done on several through InterOrdnance and called Paratrooper models.
Second, carbines firing 7.62x54r have been around for 100 years now. They do work. You will get quite alot of muzzle blast and it may kick pretty firmly, but it can be done.
And, the Soviets did invent a real deal folding stock SVD Dragunov (which has a stamped trigger group). If can be done on the PSL, too. Consider, though, that the rear of the PSL receiver is different and so a block of some sort would have to be made to adapt it to standard AK's. But I doubt it would be very tough to do.
It probably would not cost too much money to do. It would NOT negate the benefits of the PSL as far as accuracy goes, though it would reduce its power (while keeping it considerably higher than 7.62x39)
Ash