DECLARE @SQ Int(MAX)
SELECT @SQ= MAX(LEN(FIRST_NAME))  FROM #table
SELECT @SQ
-- 7

DROP TABLE #T
SELECT CASE WHEN LEN(SEQ_NUM) = 0 THEN NULL ELSE SEQ_NUM END AS REC_NUM,
CASE WHEN LEN(FIRST_NAME) = 0 THEN NULL ELSE CONVERT(CHAR(SELECT @SQ= MAX(LEN(FIRST_NAME))
 FROM #table),RTRIM(UPPER(FIRST_NAME))) END AS FIRST_NAME
 INTO #T
FROM #table