Since I have a "lesser" V8, I thought I should chime in. The 430 engine is dirt cheap but you probably wouldn't be happy with the gain in the long run. The C43 is a great engine but you have to also change the oil pan and pick up to make it work in a Crossfire. There have been guys who have swapped 500 engines into their C43 and were suprised at the results. While the C43 and 500 engine have alomost identicle numbers, the 500 engine has a broader and flatter torque curve. I really believe the best lower cost V8 is the 500 engine. With the 500 engine there is no need to change transmissions. If you change transmissons to a SRT or V8 automatic you also have to change to a 3.07 diff. 500 engines are also dirt cheap and better suited to adding boost latter if you want to. As far as being challenged 0-60 or stop light action, you will have no trouble competing with a 500 engine matched to low Crossfire n/a gearing in the trans and 3.27 rear. the weakness of the 500 engine is in top end. Adding bosst latter wen you can afford it will fix that problem. A 500 engine with a Atwood supercharger will yeild 55K performance while a turbo will surpass a 55K either way you end up with a very fast car. My kill list with my bone stock 500 engine includes Mustangs, SS Camero's, BMW's, Hemi Challenger, S65, and a Bentley Continental GT. To put a 500 engine in a Crossfire, all you need is:

Parts

500 engine (with front sump oil pan), engine harness and donor ECU, All accesories from V6 can be used
C43. C55, CLK500 exhaust manifolds
C43 fan, shroud, and upper radiator hose
12 inch pusher electric fan

Modifed Orignal Parts

cable from starter to alternator get lengthened 5 inches
A/c hose to condensor get shortened 4 inches
Stock head pipes get tweaked at muffler shop to bolt to C43 manifolds and O2 bungs welded in.

Electronics

Donor ECU get unlocked and programmed to the car
a starter button is added