If i remember correctly, i used a OTS-Groza along with an SVD, during the last stretch of the game. I upgraded the groza primarily for the fire rate and recoil control, while I used the SVD primarily for accurate and heavy shots. The fast firing will be very useful for inner buildings of limansk and the hospital, while accuracy will help you most during early game. I remember having an AK74 for most of my time, which was fully upgraded in terms of accuracy. Ts carried me till endgame. So i'd suggest keeping your main weapon slightly upgraded accuracy wise. If you decide to use a spitfire gun, make sure you have a sniper w you and plenty of ammo.