I've got a spare pair of junk heads, if you want to use them for stock to see where you can grind. I haven't checked them or anything for cracks, and to be honest with you, they are probably shot, but they are good if you need some practice stock to see how far you can go....
Do you have a flow bench? If not, pretty hard to do an effective job of porting without a flow bench, you will just end up making things worse... A porting job means more than just grinding stuff off and making it look smooth.....
If you are just polishing everything and not removing anything but surface roughness, go ahead with your heads, it is easy. If you are just port matching everything, go ahead and match the heads, you have plenty of material there you can grind off to port match everything.
*Edit I actually just realized that you were posting in the other thread about having a cracked head. I guess you already have a pair you can play around with. I might look at these heads later to see if they might be good and clean them up... they are sitting under a pile of chopped up 91 EB ex.