What parts you use and how much money you want to spend are all relevant to you intended use and your budget.
There is absolutely nothing wrong with turning down a stock crank, that was what everyone used to do before cheap offshore cranks became the rage. I have Mahle pistons in my 499" RB, but be aware they only have 1 mm, 1mm, 3mm ring width. Not what you want for a long street life or if you intend to shoot NOS on them. For street or nitrous use I would want a traditional 1/16", 1/16", 3/16" ring package.
Tom