Most aftermarket piston companies offer a variety of configurations in .040" over. What type of piston depends on the intended use of the engine.
If this will be a stock or mild buildup, then cast or hypereutectic pistons will be sufficient, and they will be inexpensive. If you intend to run a high rpm, high compression engine, or any power adder, you probably should spend the extra money for forged pistons.
As for piston shape, that will also depend on intended use. You will need to determine the desired compression ratio, then perform some equations to find out what you need.
You may want to contact several piston companies and talk to someone on the tech line. They can help you make a sound decision. For cast, look at TRW or Federal Mogul. For hypereutectic, contact KB Pistons. For forged, JE, Ross, and Wiseco are all excellent choices.
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