Not with that small of cam, it'll idle and work just fine. There are few guys running the Comp equiv (35-420-8 270/270 215/215 .533/.533 110) on basically stock motors with great results.
Some reading I pulled off another site:
"For those following along, here's the combo:
'92 LX 5.0 with 150k on it
Box-stock Cobra intake, FRPP 65mm TB, Pro-M 75mm MAF,
K&N Panel filter in stock box/no silencer
1-5/8 equal-length shorties to off-road h-pipe to 2.5-inch Super Turbo cat-back
3.55's and T-5
I got a definite kick in the pants a few years ago when I installed the Cobra intake on stock heads and cam. Well worth the effort. I wanted something more, but I didn't want to mess with the expense or hassle of new heads.
The car is daily driven in nice weather, autocrossed a lot, and also open-tracked. I wanted more low and midrange torque to get me out of corners without requiring a shift, and I didn't need it to be a high-winder.
I was encouraged by the results 5.0 magazine got out of a very similar combo in the Sep '03 issue by installing a Crane 2031 and 1.7 rockers...like 40 lb-feet at 3000 RPM (Interestingly enough when they installed Edelcbrock heads on the same cam in the next issue, power fell way off until about 4200 RPM)
Talked to a few folks and went with the Comp 270 HR Buddy Rawls often recommends as a good off-the-shelf cam for stock-head combos with balanced intake and exhaust capabilities. Part number is 35-420-8, specs are 270/270 215/215 .533/.533 on 110 LSA. I installed it dot-to-dot on a Ford Motorsport timing set, without degreeing it exactly.
I installed new Trick Flow valvesprings and a Pioneer balancer at the same time.
Had to deal with some valvetrain noise issues but it's mostly all sorted out now.
The verdict: I got what I asked for. Butt-o-meter says I have WAY more torque even as low as under 2000 RPM than I did before, with a less peaky transition at 3000 than i had with the stock cam. Interestingly seems to run out of breath a little more sharply after 5200 than the stock cam but I can't tell for sure, haven't run it that high too much yet.
It idles just a little choppier than stock, but still mild. I actually would have preferred a rattier idle but I'm not sure I can get that AND good bottom-end.
I'll take it to the track in a couple weeks but I'm not expecting miracles, for a few reasons. The last time I had it down the strip I was running about 101.5 mph but I had a lighter car...no roll bar, stock brakes, light wheels. Now I have a bar, heavier 17's, and heavier front brakes. I also had DR's before and now I don't.
I also don't know if I'll show much improvement on the dyno because the one and only dyno run I have was a little portable deal and due to miscommunication it doesn't start registering until 4600 RPM"