Good luck, other than the chance of flare this lens seems rather good. I have one but don't use it much. Mostly I now use a Bessa rangefinder.
This amount of flare should be very obvious in the viewfinder. Just hold your hand up to shield the lens and if flare is your nemesis, then this will markedly improve the viewfinder image. The Helios is a bit prone to flare, but not outrageously so.
I remember a thread on the RRF where Brian Sweeney took a Helios-103 (a different lens) which comes with lightly blued leaves in the iris and reduced flare considerably by the simple expedient of rubbing a black marker on them and replacing the front element cluster.
He shows a before/after shot of the same scene and the reduction of flare is easily seen. Could it be this Helios suffers from the same problem?
Could be an answer for you.