The Daiwa sealine models and the Senators have a LOT in common. The Daiwa 450H is indeed a kissing cousin of the Senator 113LWH (the wideframed version of the 113H). So much in fact that a lot of the internal parts are interchangeable. Alan Tani, the online god of reel maintenance and upgrading, has one of his amazing photo spreads many places online about tweaking up a Daiwa 450H (search for AlanTani, Daiwa and 450H....lots of websites host his articles). Once you see Alan's photos you will understand just how similar the reels are. His main recommendation is replace the Daiwa drags...with classic Penn carbon fiber drags.
Here is the end summary about the 450H from Alan:
"now, for a few comments...... the sealine 450H is a real diamond in the rough. let's compare daiwa sealine 450h to the 4/0 penn 113hlw. the spool size of the daiwa sealine 450h on the right hand side is about the same size as the wide spool 4/0 penn senator 113hlw. the drag range is also about the same. with greased carbon fiber drag washers, the functional drag range for both reels is 10-20#'s with an absolute maximum drag of about 25#'s. because of the risk of damage to the main gears, i would recommend keeping the drag below 20#'s. once you change out the drags, the performance of the two reels is identical. the main advantage of the daiwa sealine 450h is the aluminum frame. a similar upgrade for the penn is $80 for the frame alone. the daiwa sealine 450h is available for $120, the penn 113hlw is available for $130. with a $10 drag washer upgrade, you can have an all aluminum "4/0 wide" daiwa that will perform as well as a penn. honestly, the performance of the two reels will be identical, but because of the all aluminum frame, i will vote for the daiwa sealine 450h to edge out the penn 113hlw as the best in its class."
They are good reels. A buddy of mine brought two older versions on board last week that he bought in the mid 80s for tuna fishing off California. Very nice reels and have held up perfectly over the years. Nice drag and very sturdy. I personally would compare them to the Senators from Penn.