Fast is the key. Keep in mind that the NPCs, like monsters, are generally designed to be killed in 2d4 rounds. So, don't spend hours lovingly crafting one -- because that's the one that will get critted in a surprise attack and be dead before the initiative dice stop rolling.
That's good advice generally, but I would instead say, "Don't do so much that it is a chore. If you want to craft an NPC, craft that NPC. If not, not. It's all good." DCC is not like 3.x; i.e., you cannot get the stats "wrong".....the major homework factor has been removed. But, for special NPCs, do whatever feels right. Remember the goal is that for every minute you spend in prep, you need to get a minimum of 2 minutes play value. More is preferable.
The Purple Sorcerer generators can create higher level characters for you, BTW, which you then merely tweak to turn them into exactly what you want.
The "big names" in Shanthopal will be fully realized, but not fully compliant with the DCC character creation rules. This is fine; I expect mid-to-high-level PCs to diverge from the base rules quite a bit as well!