If you have the side rail grooves, you can use a regular SVT-40 sniper mount, just without the locking pin. From what I've read (but not tried) it works mostly Ok, you just need to fire a few shots once you've shoved it on (rubber mallet method to get it on as far as possible) to fiish "seating" it then it should hold zero. The problem comes with dis-assembly for cleaning after firing corrosive ammo.
If you want something more solid, Corwin-Arms sells the VOMZ side rail "Dragunov" style mount. You have to drill and tap to attach the mounting rail, but then the rest of the scope mount comes off relatively easily for cleaning and should return to zero when remounting.
Aparently, some have had success mounting the full POSP rig to the SVT - which has the added benefit of coming essentially pre-calibrated to the the SVT-40, which has a similar ballistic trajectory to the Dragunov (same round, slightly shorter barrel and velocity, but pretty close)... Not horribly expensive either for the whole rig:
http://corwin-arms.com/product/posp-3-9x24-scope
Not advertising for Corwin-Arms, because I have no personal experience with it myself, although I'm tempted to pick up a second SVT-40 just to try the POSP rig, because it looks like it would be effective. Even if it does involve some drill and tap to ruin any potential collector value.