need input kz440/400

I need help figuring out how to do this whole motor/carb work. I have a 1980 kz440 motor and frame that I just bought ( got it cheap and came with a title ) Just motor and frame. I also bought a 1975 kz400 full bike ( no title ) . Im trying to take both bikes and make one bike out of them. Idk if the 400 carbs will work on the 440, had a buddy tell me to find some flat slid carbs for it but other people are telling me to make a 2 into 1 carb for it. Im kinda new to the jap side of bikes and only know basics. Right now the 440 frame is sitting with the 400 front and rear end on it ( pretty much a roller with the motor in the frame but not bolted all the way down ). Im using all the 400 parts I can right now to save some money but would like to make this a café racer out of it. Did the 440 have a different motor mount for the top of the motor, I see the 400 one is a little short ( holes don't line up ) but I didn't tighten all the other bolts down yet. I do see a couple things that are different in the frame styles but as Im thinking about cafeing it, it doesn't look like to big of a deal. Im looking for some good advise/pointers in doing this. Don't want to keep taking it apart over and over. I want to get the motor and carb thing figured out and running before I start customizing it. Has anyone put kerker exhaust on a 440 or is there a better exhaust, i know kerker sounds really good on the 1000s. Im also thinking about getting a older triumph tank for it, like the way there tanks look. If anyone can help that would be cool. Thanks guys.