I think it's possible we might have a clarification problem here. When you said 268 series cam I looked in my catalog and assumed it was the 268H you were refering to. That has the specs I listed before. The XE268H extreme cam has the larger profile listed by rssschevy2. If you are using the XE series cam yes it would more closely match the RPM manifold but it would be close. My cam has .471 lift and I'm still using the regular performer manifold with pretty good idle characteristics. The larger cam and intake will sacrifice a little of your drivability (you can go to <a href="http://www.compcams.com" target="_blank">www.compcams.com</a> and look at cam characteristics ) but as mentioned the high stall converter will help. If it was my mistake looking up the specs wrong I apalogize. It does sound like a pretty tough set-up though.
BUILT FORD TOUGH