What cam should I get?

Well, the 262 has no real noticable lope..BUt it's also got no exhaust or mufflers..lol. The 368 I had ina 9.8:1 360 had a hint of an idle. But I think in a 273, you will hear the 262. Just my opinion tho. The XE cams are designed to have a nice idle, so "hearing it" is not on the top of the list. You dont have to pull a head unless you want to figure compression ratio. You wont have valve to piston trouble with the 262, the 268 you should also be ok.