I used 300lb braid as main line before. but it catches too much current. Switch to 130lb improved a bit. lighter line fishing from shore is harmful for both fish and yourself.
When fishing from shore, Land anything bigger than 7 feet depends on luck more than the gear. Pay more attention to the shore condition. Think of where to land the fish is more important. The drag is the least you need to worry. a big fish can pull any drag in the market. and it will break off if the drag is more than 20lb. If you use lever drag, do use scale to measure the drag. 20lb drag is way more than you think. usually we feel very tight drag is around 5-8lb most. We usually allow the fish run fast and further out to avoid any snags and rocks close to shore. tire them out in the deep water and bring in fast when it is done. When the braid touches a rock, 300lb braid will break like nothing.
Spinning reel is bulky and heavy. I prefer open face star drag reel. The star drag reel has brake, it will be less likely to get bird nest like the lever drag reel. But Bird nest still happens sometime. if you have a kayak or something, it helps to bring heavy weight and bait further out in the river. Casting 12oz plus a fish head far is challenging for any setup.