Zimectrin Gold (horse paste) has two meds in it.. a (one) "green pea" pea size for Standard chickens and a (one) BB size (BB gun BB) for Bantams.. not more... be careful.. Mine would not eat it on bread, they spit it out.. must taste nasty. (Give orally, careful to dose one at a time, making sure each gets just one dose... on bread or ?)
I have been told that chickens can build up an immunity to it rather quickly... (so, don't use it next time you worm).... and Ivermectin alone does not kill all worms, does not kill tapeworms. Hence the Zimectrin Gold has two medicines and the second med in it.. (can't remember the name) is the one that kills tapeworms.
Maybe use the Zimectrin Gold first.. then, ten days later use Valbazen... ?
I do believe it's the Ivermectin that kills mites as well, though, so that's helpful.
Order from Jefferslivestock.com or another on-line animal supply.. watch out for freight charges for heavy items. I have feed stores around here, three I can go to... between the three they have everything I could need.
Withhold eggs from the first dose... repeat dose ten days after first and then withhold the eggs for two more weeks.. safe on the fifteenth day after the second dose... 25th day from the first, from the start of treatment....
Good luck.