Go with 4 oz, and chuck the other humi puck. You won't need it. The beads actually give off moisture when the RH falls below 65% and absorb moisture when the RH is above 65%.

You're on the right track. I keep mine in the basement also, it stays around 65 degrees and around 65% RH. But don't freak out if it fluctuates, 5 degrees and 5 RH either way, it doesn't really matter much over the short run. Also, RH is controlled by both so a spike in Temp will bring the RH up and vice versa. If anything, I'd prefer my RH below 65 than above.

The worst thing everyone goes through when you start up your first humi and start collecting cigars is freaking out over the RH. I'm pretty sure everyone on this board did it in the beginning, I know I did. I'd check the RH, add a couple of drops of distilled water, check it again, and leave it open for a few mins. and on and on trying to keep it exact. Then I realized I was just torturing myself and it didn't make a dam bit of difference.

enjoy.