Dear Isaac:
The table KNA1 is restricted with 35 characters, if you want to use the ADRC Table (ADDR1 structure) is allowed to use 40 characters, if some data have the total length allowed in XD01/XD02 is better use ADRC table.
To join ADRC table with KNA1 use the field KNA1-KUNNR and KNA1-ADRNR in ADRC table ADRC-ADDRNUMBER.
I think is better to use ADRC table, and also this table have extra fields for Adress for the customer.
Please check it
Antonio Martinez R.