Teradata SQL - How to transpose data in one row

I have a table as below:

I currently have a query that selects records where SEQ=450 and RESULT='LT' OR SEQ=650 and RESULT='LT'. And for a particular ID, if there are both Sequences with 450 and 650 with RESULT='LT' like in this case as shown, I only keep the row with SEQ=450 and RESULT='LT'. However, what I want as a final output is also the SEQ and CODE values from the row above the 450 SEQ. like below

and if only 650 exists for an ID then,

Obviously in this case I would only choose seq=450.

The current query I have is

CREATE MULTISET VOLATILE TABLE DOM AS (
WITH cte AS (
SELECT DISTINCT ID
FROM MASTER
WHERE SEQ = 450
)

SELECT DISTINCT SCAN.ID, SCAN.SEQ, SCAN.CODE, SCAN.RESULT FROM MASTER 
WHERE (MASTER.SEQ = 450 OR (MASTER.SEQ = 650 AND NOT EXISTS (
SELECT 1 FROM cte WHERE cte.ID = MASTER.ID AND cte.ID = MASTER.ID
))) AND MASTER.RESULT ='LT' 
) WITH DATA PRIMARY INDEX (ID, SEQ) ON COMMIT PRESERVE ROWS;

Which gives me the output for this particular ID as:

How can I modify the query to also get the
other columns? Note: The SEQ_BEFORE will not always be 300 or 600, so I cannot just use that seq no. as a reference in the query.

This is how I understand the task: You want to get the data for seq 450 and 650 along with their predecessor values (seq 300 and 600 in your example) Then per ID you only want to select the row with the lesser ID of the two, so if you find only one of the two sequences 450 and 650, you show it, if there exist both, you only show 450.

Use LAG to get the predecessor's values. Use MIN OVER to get the lesser seq per ID.

select *
from
(
  select
    id, seq, result, code, 
    lag(code) over (partition by id order by seq) as code_before,
    lag(seq) over (partition by id order by seq) as seq_before
  from mytable
) with_values_before
where seq in (450, 650)
qualify seq = min(seq) over (partition by id)
order by id;