If I was you I'd run the cam out of your 273 like was suggested before. Even if it's not 100% best choice for your engine. Your engine is a work in progress. Your talking about a little porting now and later buying heads and I imagine a full build down the line pick the right cam then.
Torque isn't something your gonna have to worry too much. This engine will make about 100 lbs-ft more than your 273 and probably the same hp wise. They can be but most 360 aren't that much of a revver anyways most make peak power between 4500 rpm to 5500 rpm (300 to 400 hp) with a 5000 rpm powerband. And with your stall and gears you'll be fine and if you don't mind gears go the 3.73 and all will be better :)
