Ok, I'll give this one a shot, but it's kind of complicated...
The best way to see if the holes will line up is to take the old gas block and compare it directly to the new one by taking 2 very long pins (I used drill bits in the past) and putting them through both gas blocks side by side at the same time.
That way you can see if they are in exact alignment r.e. pin hole width and drilled hole angle. If the pins are the exact same width apart AND have no angle to the drilled hole, the blocks should both able to slide onto the pins at the same time without any real resistance, and then you are halfway there...
If they don't slide onto the same long pins (which they usually won't) at the same time, then the blocks were drilled at an angle (not uncommon), or they are drilled for the pins at different widths (very common, especially with Romanian stuff) and you stop there...
If all of those tests DO pass, then replacing the gas block is likely to be successful, but I have also seen original barrels that do not have the barrel pin divots bored deep enough to accommodate a re-pinning and you just wind up smashing and bending the pins. That doesn't just happen on Romy stuff, but also on East German, Yugos, and Polish ones, just to name a few...
Really the best bet (IMO) is to have someone TIG/MIG weld the gas block and file and fit the the lug in place to replicate and unmolested lug...