samson warpspeed 3/8" dyneema core diameter?

[Brion Toss]

Hello,
Expect about 5/16" (8mm in irrational measure).
As for relative diameter, so long as the buries are adequate, you can have significant size disparity; you just limit the strength to that of the weaker line, weakened a bit further by the intrusion of the larger line. What is the application?
Fair leads,
Brion Toss