Hey, new member here. insomnia-fueled browsing brought me to your build thread via DSHEP's thread. Just finished reviving a '73 cb175 and got to ride it yesterday, hence the browsing. nice looking work you're doing.
i would be reluctant to put those aftermarket carbs on there before trying to track down stock parts (or kits), just my .02 worth. i found an ebay auction you might find interesting:
http://www.ebay.com/itm/Honda-CL175-CB175-nos-carb-body-and-two-extra-carburetors-/350508767523?hash=item519bf35923&item=350508767523&pt=Motorcycles_Parts_Accessories&vxp=mtr#ht_500wt_1281
not a bad price and it seems like you would get what you need, and then some.
just thinking out loud about the dings and scratches in your slide: maybe some debris from the fuel talk? if your bike is like mine, it didn't have inline fuel filters when you got it, which is silly since they're so cheap and helpful. spend a couple bucks on a pair.
i was having idling issues also, rpm's were slow to fall after revving, and then would slowly drop to zero. i had the carbs cleaned, and new hardware (jets, needles, screws) installed in them, and now it runs like a dream.
hope some of that is helpful, i'm learning all of this stuff as i go! Good luck, looking forward to the next update!