I know its not easy to determinate the reality...
But what are your guesses how much HP/TQ you can expect from:

5,2 MAGNUM Stock Heads & Pistons
New Bearings & Piston Rings
Edelbrock AIR GAP or M1 Intake
750cfm Carb (Holley/BG)
a serious Camshaft
Headers

?? My stock 5.2 (with MP computer) Dakota went 14.08 @ 97. I would think with an more agressive cam, a better intake and more cfm you could see 50+ more HP. I added headers but it didn't effect ET or MPH. I think they et calculator rated my 5.2 at 256hp. Whick is about right considering it was rated at 230 and the computer claimed 28hp gains. So I'd guess you could hit 300-315.

I can't believe nobody has given the standard Moparts reply yet...

Why not just get a 360? They're everywhere.

I'd say Yuck's estimate is about right, camshaft choice might sway it a little up/down.

how serious of a cam shaft?

if you're looking for something streetable, keep a hydraulic roller with aggressive ramps and .050 duration in the 218 range or so...the comp XR265HR would be a good stick if you don't want to mess much with the heads (anything over about .520" of lift or so requires cutting the valve guides down)

use hughes #1110 springs. I'd wager an honest 320-340 HP with headers, that cam, intake and carb, and still be very streetable with decent mileage.

if you're freshening the heads, the VJ is undersized, have them open the seats up to 1.9"/1.605" (stock VJ's run small enough to run old 1.88/1.6 valve sizes). have a 75 degree throat cut done to open up the bowls, and do some bowl blending & profile the guide boss. also open up the pushrod pinch some, too...these simple mods should gain ~10-15% improvement in flow on intake side, and bigger gains on the exhaust for more power...

360cui in Germany not lying around how for your guys in the V8 paradise USA (;-)) I can have a donor 5,2 Magnum from a 1993 Jeep Grand Cherokee......