spun rod bearing = scored crank. You don't want to cut the crank. no good comes of that.
For starters the stock crank it nitrided for a harder surface. Nitriding your crank is expensive. Much cheaper to buy an engine with a good crank.
Antihero
Putting AMS garbage, and $500 ebay wheels on a Z is like dressing a Victorias Secret model in a Walmart dress and Payless shoes. You're embarrassing yourself.