If the pole is hardwood the creosote has most likely only penetrated the outer band of sapwood. Theoretically the sapwood could be sawn off, leaving a square of clean timber that could be re-sawn into smaller sizes if desired. However, in practice there are a few unknowns. The main issue is that although penetration will be largely confined to the sapwood, creosote will have penetrated more deeply via any cracks that were pre-existing in the wood at the time of treatment. Also if the pole is softwood, penetration is likely to be deeper.

Your timber trusses can be visually stress graded in situ as long as access is available and all surfaces are visible. Australian Standard 2858 contains grading rules for softwoods, and Australian Standard 2082 for hardwoods. We don't have a contact in the Newcastle area but we suggest you contact Timber Training at Creswick.