Well we went to the store yesterday and talked to a sales person and decided on the cam I'm getting. We picked a crane with 272. We were going to go with 278 but I didn't think my engine compression was high enough. It's 130052 on summit. I can't wait til my b'day next week!
Eh- when you're talking Advertised Duration, you're talking Greek to me... and most other professional engine buiders. Stick to the .050 duration figures and you'll become more familiar with cams in general. The problem is, every cam manufacturer measures their advertised duraton at different lift points. For example:
Say Crane has a 280 cam... better yet, we'll use your 272 cam for example. Crane's 272 adv. Duration cam lists as 216* duration at .050 lift. Also having a 110 lobe separation and probably a 108 intake centerline. NOW- we look at Lunati who shows a 282 advertised cam. Think it will be a bigger cam??? Not at all. Matter of fact it's considerably smaller. Lunati lists the 282 as 208* at .050 lift. with a 112 lobe sep and 107 intake centerline. Obviously two totally different animals! But- if you were to follow the advertised duration you would have though you had a bigger cam! i learned my lesson when i was about your age ordering my 1st cam for my '67 Ranchero and being UTTERLY disappointed when I installed the Crane Fireball II the moron counterman suggested for me. I had asked for a cam with the larget possible duration in under .500 valve lift.... and what he gave me DEFINATELY wasn't it, and in reality the cam I WAS asking for was really trouble anyways! After that I dedicated myself to learning as much as possible about cams. And that I have, and am still learning.
To explain the difference in why these two cams advertise the way they do but are much different lead to how they were measured. You see, there is no standard as to which the cam manufacturer measures their advertised duration. One company may measures at .004 lifter rise wheras another will measure theirs at .007 lifter rise. So advertised duration is really a loose subject with alot of professional engine builders. The best comparison is the .050 figure. Sometimes the advertised figure is helpful in determining how steep of a ramp the lobe has which is really only a necessity for pro-race engines.
Another fault i see is the fact that you have chosen a single pattern cam (meaning the duration for the exh and intake are the same) to use in a stock and non-ported head application. Yes, they do work, but it's been proven that the single pattern cam paired up with Ford's cruddy exh port flow actually chokes the cam's performance. And..... single pattern cams tend to have a later and narrow powerband making them kinda a nusience when you want the power. Dual pattern cams are more broad and are typically better tailored to the engine it's designed for. (like a SBF with crappy exh port flow)
Another term loosely used is 'streetable' as in "that's a streetable cam". Well, everyone's perception of a steetable cam is different. Some think that a lopey cam isn't streetable. I've got a .496/.512 lift 224/234 @.050 cam in my Mustang II and, to me, it's very streetable. But again, it depends on what you're willing to put up with sitting in traffic...
Long story short, don't listen to the idiot at the counter. The days are long gone when parts houses acutally kept knowlegeable staff on the payroll. (though there are damn few that still are) Talk to an engine builder or the best yet, call the cam manufacturer direct. Comp, Crane, Lunati, etc.. have hotlines where you can contact them for your specific application.
Personally I'd choose a 214/224 @ .050 duration with .472/.496 lift and 112 Centerline to run in your II. Summit use to carry this cam but no longer does. PAW (Performance Automotive Warehouse) however does carry this cam and it's p/n is 11326 and can be had as a cam/lifter combo for under a Ben Franklin. I've been running PAW's SSI cams for years and have not had a single problem. I've used this particular cam in a frw friends' cars aswell as my brother's daily driver '70 Maverick.
I hope I have been of some help.