I replaced my slant 6 with a 5.9 magnum last year and bought a new 625 cfm street demon carb. Due to no tuning, used engine, and ignorance. I blew both headgaskets. The 360 came back out and get bored .030 over with 10.5 pistons, Hughes EQ heads with 2.02 and 1.62 valves. Hughes cam .539/ .549...