Proposed cam specs
I think anything above a .500 final lift sounds too high on a flat tappet, but as stated above, because of the roller tappet lifters, your pushrod geometry changes from the lifter to the rocker and you will shave something like .023" from the final lift.
If it were a flat tappet, I'd go with a 489 501 or something like that, but it sounds like it's a good lift number for a roller 360.
The duration of open to close on the lobes being in the 220 degree crank rotation should be ok with a 360 stroke, the lobe sep should help some from overlap of intake/ exhaust valves being open at the same time in the cycle some, but that's why headers are suggested above. Header's individual runner tubes will help scavenge the unburnt fuel back into the cylinder.
Sort of a double edged sword there. You can gain a little HP there, but you lose drivability and most good fitting headers that don't hang incredibly low are not cheap. I sort of leave them alone.
If you have manual steering and you aren't afraid of changing the exhaust up front, a pair of 360 Truck manifolds with rear dump are nice and they are inexpensive. Magnum manifolds well, too. I'm running truck manifolds with power steering, but I had to modify the bottom rear end of the manifold near the exit and shave a small amount from the cast iron on the steering box to give it a little more room, comfortably, but they work well and nothing touches. When the engine moves under stall, it moves further away from it and keeps it's distance.
I'm with Moper on this. Though I myself would like more gear. 3.21/3.23
I agree. No matter what, I think you should eventually plan on a 3.21 or 3.23 gear set for what you're going for. Don't bother spending cash on a sure-grip. Just find a good, used open carrier for an 8 1/4 with 3.21's or an 8 3/4 with 3.23's. Whichever axle you have. If you have a 7 1/4, just look for a complete 8 1/4 with 3.21's.
I think this cam is a good buy for you and will give you the opportunity to move up in gears to help your cruising/ acceleration. The gears down in the 2's help highway, but actually hurt MPG in town as well as power, due to the added throttle position needed and converter slipping to get the car moving.
I think you are on the right track here. I don't know what the primary size is on a 600 holley, but I wouldn't be surprised if you got more response and higher HP and TQ from something in the 625 range with smaller primaries for the street, but if you've already got the carb, run it.
Does the cam have any initial advance built into it? That can help some, too.
