Thanks, Quincy. I'd wondered about "sword" and "spear." I take it if "st" can't go with "sk," then just plain "s" can only go with "s" and not with "sp", right? Rats. I think I've stuck to stressed syllables, though.
I'm working on another one, and it's got a "b/br/bl" line. I may have to invoke the Drunken Scop's Rule, a little-known rule (since I just made it up) which allows for minor cheating.