The picture looks like paired intake ports to me, I'd be shocked if someone can calculate a runner size for that will give harmonic benefits anymore accurately than me randomly saying 4". 8" 12.324", 53". If anything I'd expect the harmonic length to either need to halved or doubled, but the port shape can't be great for harmonic tuning.
Its a turbo engine, don't over think it as the harmonic benefit will really only have a very tight range of rpm for noticeable benefit, assuming you can even figure out what the common ports want. That all said, I'm going to be building an intake for my turbo engine using the same logic and data I posted above, but if I find fitment issues, I'll shrug my shoulders and shorten the tubes as needed, writing it off as a nice idea.
**IF someone has ran real world testing (not calc's or models) of various lengths of the common port intake with similar cam spec's, THAT is the data you'd like to see and use.
