So, I'm looking to do a bit of scratch ship building and was curious if anyone knew how basic hull stats were related to the hull's SP value.

Size, weapon capacity, pre installed parts. Use what exists as guidelines for size and crew and an average of sorts to start as your base line cost. I can only suggest methods of estimation sorry I have no easy break down

Though in general, yes. As a base, the better the ship the more SP it has. Sometimes though it's because of pre-installed components raising the SP cost.

SP values appear to be estimated, rather than calculated. Though you're right, I should try to derive them again.

If I can find some time this weekend I'll see about helping out with this little project. I like ships.

Are you implying that FFG would stoop to using actual math to calculate numerical values of things?