Firstly, this is a UK-based board
. We go by GMT, which is the standard measure of time for the whole world... you and your fancy "Pacific Daylight" nonsense...
But seriously, the board is set to GMT as default.
As for Ork armou
) I would say that most pre-Heresy Orks would not look any different from their post-Heresy descendants. Their armour and weaponry is cobbled together from basic scraps, and the "science" behind it is encoded into their genetic memory - they don't really ever discover new things, they just build what it occurs to them to build from memory.
If you want to go the scavenged route, once again I stress that you should just follow the normal rules for PH Space Marines and Imperial Army weapons and armour. They'd only have access to salvage which would have been in use in the expeditionary fleets.