You should be fine casting that sort of weight. Whether that size sinker is enough would depend on the wind and water movement. If you don't need to cast far you could probably get away with a bit bigger sinker as long as it's just a gentle lob. Otherwise, if you need better grip try and find some 2oz grapnel sinkers, although I'm not sure they're readily available around here, Let's Go Fishin would be your best bet.
