What teapots will work, can I modify any two carbs or do they have to be matched?

I have heard of Lincoln carbs working, what's the scoop?  Can I find two Lincoln carbs and modify or do they need to be matched?

I have also heard of the WCFB's working, again do they have to be off a '56 Merc or will any WCFB work and again do they have to be matched? 

Thanks for any help and carification.