This post was started in May and the OP hasn't responded. What did you end up with?
And my answer: get the V6 because you can add a blower to it in the future and have 450hp without being at the engine limits.
2008 Bullitt|Roush M90 w/2.57 pulley & CAI; 90mm MAF; Steeda-UCA, LCAs, Ultralites, links, mounts; MM CC plates; Bilsteins; GT500 FCAs; Brembos; Roush shifter; GT500KR axle back; etc
1969 Coupe Restomod-never complete!
2008 Power Wheels Bullitt Clone
Mustangs from the past: 66 coupe, 69 Coupe, 69 Grande, 2001 Bullitt, 2011 V6