100% second Roger's advice thus far...

Key points...!!!...you have massive snow load potential in your area for that species and span with the size timbers designated...

King Post (or related) truss system...or...interior center post required...

Drawings need to be present for even moderate good advice...PE involvement highly recommended for novice frame projects. Note, I personally have 40 years at timber framing and all "new frame designs" are looked at by a PE...

I don't use oblique bracing in 99.9% of my designs (aka more Asian-Middle Eastern-Eurasian in motif and modality) so will just "hang back" and follow along for the most part...

Good Luck,

j