I did install B wings on an A model rv-3 ,I did this several years ago so I don't remember some of the particulars, here are some of the things needed to be done.
replace fuselage carry thru bulkhead , I replaced rear spar carry thru straps although you may not need to if your able to set incidence with exsisting hole. another reason for me replacing is I went to larger material. as you already know you will have to rework fuel system. changing bulkhead is not particulary difficult but proper alignment for incidence can be time consuming alot depends on the quality of original build. I would suggest having a good small angle drill. At the same time of wing replacement I added electric flaps .
This conversion took some time with all the things needed to be done .
Good luck Jerry