I am looking to try and get more speed out of my 1980 Newport II with the ZA50, I get about 30 if I am on a flat/kinda downward hill and want to get it to 40-45 as cheap as possible, but willing to buy nice parts when necessary. My goal is to try and keep it looking as original as possible because I love the look. What are the best upgrades I should do to try and keep the look close to the same, but get some higher speeds?? Thank You!