I'm looking for opinions on running a Comp Cams XE268 in a mild 440 with 9.0 compression ratio, 915 stock heads, & 6 pack in 71 Charger. I'm interested in idle quality, streetability, and vacuum as I have power brakes. I do want to maintain the muscle car sound and have no plans on racing. Just want a nice ride and sound. I am currently running a 280 purple shaft which is low on vacuum. Thanks in advance for advice and opinions.