I am not an Olds man however I believe that the 403 is a version of the small olds motor based on the 330.The weak link in these motors is the cast pistons.I believe that if you build one up this is the weakest link.There are Aluminim E-heads available for this engine however you will have to modify the intake manifold. Mondello in California sells a package for this engine.I would contact him for information on building a strong Olds motor.
However I have two T/As that came equipped with 403s ,I elected to replace them with 400-455 Poncho Power - a very easy swap.Good Luck ,
Mark B.a.k.a. Cruiser later
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