Small block use a ma Mopar rad. I use a large one from a Dodge van in my 73 This past weekend it was 93, with hummidity near 70% drove it around with a 195 stat and never went over 200 race it that way too with gears and short tire it may hit 200 cruising at 3800 at 65-70. A good recore with more fins in between the tubes makes for a better rad. Brass/copper.Small block 360