With a street engine, the main concerns are:
Transmission type (auto or manual, and if auto - stock or "loose" converter)
Rear gear ratio
Need for vacuum accessories (power brakes, factory a/c)
How the car is going to be used (street, highway, race... i.e. what rpm range is it going to "live" in most of the time?)
Also, to some degree --- compression ratio. (If you're pushing the limit on compression you're going to want a relatively late intake closing event to help control peak cylinder pressure - and thus tendency towards detonation - you can accomplish this with a "longer" duration cam, or by installing the cam a little retarded. Both of those however tend to shift the peak VE (maximum torque) to a higher rpm.)
All those things have a bearing on rpm range and driveability.
Cam selection is a big deal and it will pay you to spend lots of time thinking about all the things that go into it and deciding what's right for YOUR situation. This is definitely one area where it doesn't pay to just copy what someone else has done.
I just "ran" your numbers (455 +0.30, zero deck, flat-tops, 7k3 heads) and if those heads actually have the factory nominal chambers (96 cc's) that will put you at 9.45:1 compression. That's close to the limit with iron heads (in my opinion) so you're probably going to want "enough" intake duration to manage pressure. The zero-deck is going to help you there because it promotes cylinder turbulence and masks sharp edges at the top of the bore, both of which help to prevent detonation. You've also got a manual trans and 3.36 gears, so you don't have to worry about converter stall for launch (if you're going to race it any). That leaves the question of power accessories. Do you have power brakes and/or factory a/c? For brakes you'll want to keep idle vacuum above 15 inches or so.
I fired up Engine Analyzer and ran some simulations. CompCams XE 274 grind will make some good torque and power, but idle vacuum is low for brakes - around 13 inches. Also the HP peak occurs between 5000 and 5500 rpm which in my view is WAY too risky in a 455 with stock rods. Good forged steel, no problem - but not with stock. Dropping back to Comp's XE 262 looks a little more reasonable. Peak power happens around 4700 rpm and it makes around 16 inches of vacuum. Peak power and peak torque are less than with the XE 274 though. Lunati's 307A2 looks better. It makes about 10 more HP than the XE 262 and also has a wider/smoother torque curve - probably because it has a wider LSA (112) vs. the XE 262 (110). Vacuum is also passable at 16 inches. Peak power (439) with the Lunati happens at 4900 rpm, peak torque (495) at 3400. The Crower 60243 is borderline. Installed 4 degrees advanced the power peak (443) happens just above 5000, torque is gorgeous - peak (504) occurs at 3700 and is nice, wide, and flat. It only makes 14" of vacuum though. Advancing it a little more (6 degrees) pulls the power peak back to 4900 and costs you about 6 HP, but the torque is even better - 507 @ 3500 and it's still making 470 at 4900. Vacuum is still between 14 and 15 though. To my surprise, the Crower 60918 looks pretty good too. It makes 425 HP at 4800, 494 lb.ft. at 3400, with 17" of vacuum. The torque curve isn't as consistent and pretty as the 60243, having a dip between 3700 and 4400, but other than that it looks pretty nice - and shouldn't have any problems with brakes. That's with the cam installed "straight up". I played with retarding it a little and that shifted the peak power slightly higher, but didn't make much difference otherwise - in fact torque looked a little worse.
In your case, if you've got power brakes and this is going to be mostly a street car, I'd go with the Crower 60918 or the Lunati. If power brakes aren't a concern (or if you're willing to solve that problem "independently" like I did with something like a hydroboost system), then in a flat tappet cam I'd definitely go with the Crower 60243 and advance it about 4-5 degrees.
Just to make your mouth water a little bit, I ran one more simulation with "my" cam. Peak power was 465 at 5350
peak torque was 508 at 3700.
Vacuum was only 13.5" though...