Did they use different model Nikki carbs?
What should I look for once I remove the carb?
Will I need a rebuild kit?
Or will I need to replace the carb?
You can attempt to repair or replace. If you go the replacement route you will save yourself a lot of time and frustration (potentially) due to the fact the if you do not have all the tools, knowledge, experience, etc. you will spend a lot of time & money acquiring all that you need and yes, you will need a carburetor kit. The two screws that hold the bowl on the Nikki carburetor are unbelievably tight for their size and many times people will use the wrong size screwdriver to remove them and damage them in the process. Once you get the bowl off, the carburetor is relatively simple but you must know what you are looking at, however youtube has some good videos (time investment) that you can educate yourself by watching. In this day and age of ethanol in our fuel you will want to use an ultrasonic cleaner to clean the carburetor (financial investment) and Harbor Freight has a cleaner that I have used with good success. When you remove the bowl, take notice if there is a build-up of white or gray deposits. If you see a lot of deposit, do yourself a favor and replace the carburetor.
A new carburetor starts at around $100.00 give or take a little but you can bolt it on in minutes, drain all the old fuel from the tank first, put fresh fuel and a new air filter and be good to go. It's your choice and good luck either way you go.