Swapping a 350 for the 455 in my 71 Skylark. I have followed the suggestions on buickperformance, but I have a question not covered there. With the larger fan shroud I can put in a larger fan blade. Should I replace the 18 inch fan blade for a 20 inch? I want to keep the stock appearance, so electric fans are out of the question. I did purchase a 4 row aluminum radiator, so the 18 inch may be sufficient. The BOP Swap meet show is Sunday here in Chicago, so looking for opinions. Thanks, Chris