Sorry but the best option is to sell it and buy an SLR-107FR, or if it must be Russian, get an SGL-21/61 and have the folding stock installed.
You will pay a premium for Russian barrel components and folding trunnion, so if you want those parts at a reasonable cost you'll be buying Bulgarian surplus any way - you won't end up with a 100% Russian rifle unless you pay the premium. APEX, Robert RTG and K-Var typically have the barrel components of gas block, FSB, muzzle brake, and HG retainer - but in total these add up to a few hundred dollars now.
In my experience even if your Saiga has pinned barrel components, they may need to be cut off unless you have a press. Mine were the dimpled components, and I tried drilling out the dimples first, but this didn't work. I ended up slicing them down the middle with a Dremel cutting wheel, then split them open with a screwdriver, then they slid off the barrel by hand.
You will need 3mm bits to drill the pin channels, and this can be carefully done with a hand drill, but drill press is best.
Generally the Bulgarian barrel components will fit well enough that you can knock them on with a plastic dead blow hammer and get them positioned correctly with ease - I recommend polishing the barrel channel in the components and using anti-seize compound. Check with calipers prior to installation to make sure the components are not undersized, you may have to run an emery cloth to them - the press fit tolerance is something like .003-.004", anything less and they might bind up.
If your Saiga barrel has the side channel cuts for the handguard retainer you are ahead of the game. Some don't, If the cuts are there you will still need to locate the retainer and cut a pin channel. In my case I found a suitable round file that fit the channel on another AK, then worked it by hand gradually. I determined the correct point of the channel by installing the handguard and retainer, scribing a mark at the face of the retainer, then measuring the distance from the retainer face to the center of the pin. Then remove the retainer, and scribe a center point mark at the distance you measured from the face scribe. Using your center point scribe you can began filing Stop filing when the retainer fit is tight enough that it requires use of the cleaning kit tool to open/close, otherwise you may end up with a floppy retainer lever. Use a true AK-74 handguard if possible for fitting the retainer, you do not want to fit the retainer to a non-stanndard handguard e.g. Tapco.
I did the full conversion on a Saiga .223 back when AK-74 parts kits were about $100/ea, so I just bought a couple. In hindsight given the amount of work involved I should have just bought an SLR-106FR.
If you do the conversion I would agree on swapping out the trigger guard/mag catch, or at least buy one of the milled Saiga trigger guards from Carolina Shooter Supply. The reworked sporter trigger guard isn't really dimensionally correct (a bit too small) and likes to bend when the pistol grip nut is cranked down, allowing the pistol grip to loosen up again over time..