Both are good platforms. The PI 2V takes to bolt ons/mods way better than ppl give it credit for and the old 5.0 is just a proven winner. The 4V will go right into the 11s with the right setup without touching the heads/cams/intake.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.