ya proly should go with a 7' mh. im not a swim bait expert lol but thats what i would use because your gona want to have some backbone and hook setting power. for my swimbaits i use them on a 6'6'' mh rod. they work just fine on it too.
ya iv been using them bass magics and i also have used my big castaic one too but i havent caught a fish on neither one. using the small ones should still do great on a 6'6'' mh but id like to set the hook on one with that castaic one and see how it does.
6'6 MH you would be fighting the swimbait more then a fish. What size swimbaits are you throwing? For 6" and under a 7' Heavy will work you will fight the rod a little bit but it will get by. As you go up from the 6" the Okuma GS-C-7111H or XH for ROF 12 etc.... This is a "low dollar" 99.00 swimbait stick that launches the big baits very well and sensative enough to fill the bait tail kicking when slow rolling.
Trust me forcing a MH heavy standard rod is very Fatiguing, you will have 1/4 the casting distance and not much rod left to fight the fish plus its exhausting as you have to work VERY HARD with that rod. The okuma I can chunk out a HUD a mile and just not have the fatigue at the end of the day!
If you are using swim baits under 1 ounce, like a 5 ' to 6" Basstrix paddletail or the knock offs, then a standard 6'6" to 7' medium heavy to heavy bait casting rod rated to 20 lb line and up to 1 oz lures will work OK.
For swimbaits that weigh over 1 ounce and up to 5 ounces, then you need a rod built to cast heavy lures effectively. The Okuma rods mentioned are very good for the money. https://www.thebassholes.com/bassin-f...p?topic=3040.0