Hi musteq,
Natural Talalay and Blended Talalay will be very similar with the exception that blended has a slightly lower compression modulus which means that it would compress with weight a little more and be a little more pressure relieving. They would be quite close in the same ILD though.
There would also be some difference because all natural Talalay is not as consistent in its ILD rating and it comes in slightly different firmness levels (N1 - N5 which you can see here) but you should be able to get quite close and I know that Shawn will be happy to talk to you more about this.
I should also mention that there is no such thing as organic Talalay … only organic Dunlop. There’s more about this in post #6 here.
Phoenix