[CQ-Contest] WPX question

[Georgens, Tom]

Hello -

I am planning to make a few contacts in the WPX contest to check out a
new radio and I have a call sign question.  Although I have a US call
(W2SC), I also hold a valid international call.  Is it legal to sign
W6/8P9JG?  I know that I have worked W2/8P6(something) before.

Assuming it is legal to use the 8P call portable, I know I can use any
US prefix.  However, do I have to use a prefix with the number 6 if I am
California.  Specifically, could I sign AF1/8P9JG?

I was planning to choose a low probability prefix and was trying to
understand my options.  

Thanks and 73

Tom W2SC