Auto Restorer magazine is doing a 4-part article on this specific topic right now. Part 2 just came out with the newest edition. Good information. Also, you might want to check out Santucci's book on the subject called "Chevrolet Inline Six-Cylinder Power Manual". The book addresses 194,215,230,250 and 292 engines, but I'm sure it would have some good tips for a 235 as well.