On The Vintage 6 Mustang facebook page Aron Cox has a 250 with the head & a turbo ser up he's working on but I don't think he has posted any kind of numbers for it yet . I think he may still be working on the turbo set up .
He did have a log headed ,turbo charged 200 that made stupid power, but I think he sold that eng to finance this 250 build .
These 200's are so puny any way any extra power is great . You want some noticable power from your stock 200 ,just slap a 2300 Sniper on it . Fairley easy kinda , ,not cheap but that's debatable for the power you get to me ,& it won't be problem free . Put it on any kind of improved head & i suspect the power out put would be even more noticable .
Nothing you do to that six for more power is going to be cheap . I just got a Paxton up & going on my stock small log headed 200 & boy that thing runs like I put a v8 in it .
About the cheapest thing you can do for more power is a header or cam anything else plan on 2 to 4 grand. Be it a better head, a Sniper, a Paxton , a turbo set up or what ever .