Recalibration *may be* required if porting is done. However, I've heard through some channels that the maximum the stock MAF body can be ported is 61mm. That's it, and by looking at a LOT of stock MAFs in my time, I believe it. The custom Pro-Flo's are only ~$200, and they're 77mm if I remember correctly. Why not save the time and effort and go that way? FWIW, the Pro-Flo meters are calibrated slightly lean in order to maximize HP, or it's been so in the past. Granatelli's aren't bad either.
You could just get a Cobra (1993) MAF and call it done, too.
