Anything in the 212/218 with a mild LSA of 114ish will do what you want on a stock stall converter. BTR, texas speed or comp cams all sell camshafts like that. Even slightly smaller will get a okay bump in power.

You'll need new valve springs, head gaskets, push rods and all that stuff. So half the budget is already gone. The rest will be spent on a tune and possibly slightly larger fuel injectors.

If you want more out of it than that your budget needs several hundred more dollars. A good set of headers and exhaust will help it make a little more power.

Remember that is 285 at the flywheel, so it's maybe making 220-240 at the rear tire. Add a camshaft and tune with maybe some exhaust work and it'll be up around 280-300hp to the tire and 340ish at the crank at a guess.