This isn't for my 5.45, it's for my saiga 308.  Going to install an AK74 front sight block on it after I turn down the barrel for proper fit.  Would a 4 piece or standard ak74 brake work better for this?

What's the barrel length going to be?

I'm in the process of getting a 308 converted myself, and have chosen the Bulgarian slotted flash suppressor. I'm going this route because I believe that managing that 308 flash is more important than
recoil compensation; as I'm far from recoil sensitive. But, I can always switch to the 74 brake if the need arises.

My vote is your flavor of flash suppressor, or keep it somewhat commie and go with the Bulgarian hider. The four-piece, from what I have read, doesnt do much for flash.

Yeah, we have to pick one or the other.  Difficult/impossible to get both.  I have the 16" barrel so a nice big flash from the barrel.  I like the idea of fast follow up shots, but I don't relish increased noise from the shooter's perspective.  I figure an ak74 brake will be the most cost effective, just seeing if the bulgy 4 piece is any better for this purpose.  The $170 bolt on from carolina shooters supply look intriguing but just too expensive.

The Bulgy 4 part is much more of a back pressure booster than a brake. How much barrel is going to be left after you're all done? If it's 4” or less I'd go with the 4 piece, otherwise the standard AK74 brake should be fine.

With a 16” .308 you're going to get plenty of blast no matter what you do. BSW

Some people have claimed that the bolt on 308 muzzle brake makes the 16" S308 feel like a WASR in terms of recoil.  The blast isn't a big problem as I understand it takes at least 19" of barrel to mitigate the flash.