If it is a holley, it is one of the easiest carbs you will find to rebuild. Whenever I rebuild a carb I disassemble and bring all parts to a small engine repair shop to be sonic cleaned. You can buy the carb cleaner dip can but I like the sonic cleaning better and often is cheaper. When i had my outboard carb parts sonic cleaned i think it cost me 7 bucks. Something silly like that. Marine repair shops might have this type of cleaner tool but the one near me , for some reason, won't clean it unless they are rebuilding it.
When rebuilding the carb take special note of the metering block gasket. There will be a few different ones that look almost identical. Save each gasket and note which way they face in relation to the carb so you can match up the right ones and install the new one the correct way. Instead of turning the carb upside down to empty the fuel, just take one of the lower bowl screws out and all the fuell will empty from that hole. Coat the bowl gasket with a tiny miniscule amount of Vaseline so it doesn't stick to the carb bowl next time. You will soon see what I mean. I wouldn't take apart the base plate butterflies unless you are having problems in that area. The kit will come with new gaskets, a new power valve, and new needle and seat or two depending on the model carb. These parts are generally all you need to change as well as cleaning all pieces to get a brand new like carb. Extra parts left in the kit bag are normal with any rebuild kit so dont be worried. I would equate a holley rebuild with a snap together model. It all makes sense as to how it goes together. I am sure you can find about a million you tube vids of a holley rebuild that i would recommend you peruse. I always find it helps me to get a sneak peek at what i am getting into. Good luck