A flash on these cars can be done but IMO a waste of time, the gains you'll get aren't worth losing your warranty or putting engine in jepoardy. I tuned my Mustang coputer through the my computer & an EEC tuner software, it was an NA motor. You can modify the timing, fuel and spark tables to get a bit more power. I tuned mine because it was a 332ci stroker 450HP motor with a lot of performance parts! You need to be very careful though because the gains come from running the A/F mixture a bit leaner and adding more timing, which narrows the safety margin. I don't see @ 10HP being worth the risk in these behemouths what will you see a fraction of a second faster car?
A SC or even better turbo either with an intercooler would be a great way to go but I know nothing of what is in the short block. Are rods and crank steel, pistons hypereutetic or forged? You can use either SC or turbo with weaker short block parts but just make sure you have a safe tune. These are probably better ways to go and if I were going to consinder one I'd like at something like a STS turbo.