Searching for a BLDC or AC servo Controller

[AFAIK]

Have you checked the App notes on the semiconductor sites?
Freescale
Training Information Page
Motor Control Brushless DC (BLDC) Motor Solutions By Freescale
Or Picmicro have a few
http://ww1.microchip.com/downloads/e...C%2000957a.pdf
Al.

Would there need to be much modification to make these designs work for AC servos?

[Al_The_Man]

Probably alot depends on whether you want to close the loop in the drive, If so you probably need to go with a Dsp based design, for open loop drive where the loop is closed via motor feedback to the controller then some thing like the Motorola MC33033P would work.
Al.