Hi,
It's a good plan you have so far.
The famous Durock Alpacas are just a recolour of their existing nameless linear line L2-L7. In fact, all other things being equal [colour and material], they were basically the same design except for spring weight.
Things have changed a little with the introduction of their V2 linears, but they aren't much different.
So we're talking one overarching design for most Durock linears of the past year and a half.
Durock linears in general sound great once lubed and filmed.
It's too bad I just sold my Alpacas, as I could have sold you mine. [They were V1 though, and everybody wants V2 now].
I still have my Silent Alpacas, but Apex Keyboards should be restocking periodically with Alpacas of all types.
DeskHero.ca is having an 8%-off switch sale right now. Code SWITCHSALE8 at checkout
You can pick up Durock linears like Seal, FFFF linear, and the elusive Mauve. Any of those should be excellent choices for your build. I had H1 switches, which are probably similar to Seal, and they were great. FFFF linear has good reviews, and Mauve was considered the best linear for a period of time.
So I would get those.
If not Durock, I think SP Star linears are great. I like the weight of the SP Star Nana, which also sounds decent in stock form, especially on a polycarb plate. [Like KBD67 Lite].