Thought on a magnum build

IMO,
The DC509 is not for a 5.2, especially not for an automatic car, unless your pockets are deep.
I ran that cam (the 292/108) in my 367-4speed, at 11.3 Scr, and it was still soft on the bottom. My 509 measured 248/[email protected] You need a lot of Scr to make that work. But worse is that the Power is up around 5400, and you're 1>2 shift will probably like to be around 5800 or more which means, you're gonna have to do some oiling mods to help keep rod-bearings in her.
With an auto, you're gonna need a minimum 3.91 rear gear and a much higher than stock stall. and Your trans is gonna need to beefed up, and the Governor changed, and if you have 7260 U-joints, you better have a driveshaft loop, and you better have the biggest tires on the back that fit into the tubs, with the springs moved over.
and, On the front, yur gonna need the widest tires you can fit, and disc brakes, and make doggone sure that the suspension and steering are up to the task, and Have fun with your cooling system.
Why all this?
well ....... when you nail that gas-pedal, with that cam, as soon as she gets up on the cam, things tend to happen in a hurry, and top of Second gear is 85mph with those 3.91s, about 4/5 seconds from 45, and if yur in a 45mph zone, yur gonna have to use both feet on the brake pedal to get slowed back down. And that's assuming the car goes straight in both directions.
If you have a small-tub car, forget about the 509 cam. about the biggest tire you can put on the back is a 255, until you move the springs, and then maybe 275s maybe. My 367 annihilated those in one summer.

IMO, leave the stock cam in her, but put her in at "straight up", or up to 4* advanced, which means you can put just about any old dualplane on it., and you don't need headers anymore, which with the 509 you would have to have, even just to make it worthwhile to run that cam; with logs, you forfeit the 76* of overlap....... If you give up that overlap, you might as well put a cam in there ~3 sizes smaller. ........... which I highly recommend anyway, lol.
IMO
If you just gotta have a cam, then;
after you get your Exact Scr worked out, Plug a high-energy 224/230 @108 to 106LSA, into the Wallace Calculator, and see how the cylinder pressure might come in. I mean it might be too high. and you don't want to find that out after you already bought the thing.