i posted this elsewhere but i'll repeat it. I recently built up some 781's that needed and got everything. Manley 2.19/1.88 valves, comp springs and new everything else. Bought the heads for $100. Total cost when done including purchase price was just over $1100. No porting, just bowl hawg to somewhat match up the port to the bigger valve. I could have gotten patriot alum for what?? $1400??
My theory is that if you are gonna just build a cheapo stock valve / mild spring / low rpm BBC then use the 781's but anything more and step up to the aluminum as others mentioned before you have a lot of money tied up in iron!!
brian