I have the XE275HL-10 in my 383 and it is just fine. I have an Edelbrock Performer RPM with a Holley 750, ported 452 heads, 1.6 roller rockers resulting in .560" lift, a set of TTI 1-7/8" headers, a 3" TTI exhaust system with Magnaflow mufflers and 3.55 gears in the rear end with a Sure Grip. I...