Wasn't going to, but okay, I'll say something. There still are SN95 '01 Bullitt owners on the Bullitt board I visit...no ragtops there, all manual gearboxes. The 4.6 seems to be a long life engine, some Bullitt alone parts seem hard to find, but overall seem okay...150,000 miles with no problems have been reported. But keep in mind, Bullitt owners tend to be a generation or two ahead of the Mustang age group...people who don't tend to beat on Mustangs like younger owners do.
How tall are you? At 6'3", I found not enough legroom in the SN95 Cobra of a friend...much smaller inside than my '09 SN197.
The Mustang aftermarket is huge, and Ford made a potload of SN95's...so wrecked-em yard and other parts should be easily available.
I know zilch about the ecoboost engines...
Click here to read pages of board talk about mechanical issues:
https://www.imboc.com/forums/01-mechanical-issues.92/