one thing I've found that helps valve springs on these heads, specially after cutting spring pockets deeper, is to grind a small groove in the lower side of the spring pocket to let oil escape from under the spring. Otherwise the oil will sit in the pocket and cook the bottom of the spring. By allowing the oil to flow, you help keep the spring cooler. Fiat's right...SOP on these heads is to remove the ex. vane. Big port volume, not real good velocity...need a lot of RPM for NA smaller motors (under 500 ci) but will work on blower app. After clean up, ex port is good for blower motor. Chambers need a lot of attention.
Depending on boost, there's a kit that someone makes that allows you to attach a boss on the inside of a standard block so you can use the extra two head bolt holes.