Yeah the skills are a little hinky.
3.0e Alchemy
3.5e Craft(Alchemy)
= easy
3.0e Knowledge(Architecture) + Knowledge(Engineering)
3.5e Knowledge(Architecture+Engineering)
= saves the ranks, rules as intended.
Getting a craft as a class skill from this list :
Craft (armorsmithing, blacksmithing, gemcutting, locksmithing, metalworking, trapmaking, or weaponmaking)
can be done the way you're going about it.
... but ... getting to the 8 ranks part
early (!) requires some stretching.
Major Bloodline is one way.
Primary Contact feat, and it's prereq Favored feat, is the ~famous "That Feat In Cityscape" way.
Luckily both feat can be retrained away in one level or two.
Otherwise you gotta go PLZ's bard cheese, or worse.