i would not change heads to reduce weight. A cast iron intake yes but heads are not worth the effort of changing.
Keep this in the back of your mind at all times. I have taken several engines apart to replace the heads and found out I was doing a full engine rebuild. Not a bad thing but once you got it apart you may see some things that will need to be worked out before going back.
Heads have the right numbers even if they are off one number higher or lower than everyone else. I woul dbet they are low quailty heads.
If you are not a good mechanic I would skip the cheap heads and go with the cheap edelbrock heads. they are around a grand and will work well Procomps are cheaper but not really something i would recommend as a first timer swap as you want something will just work out of the box and not fail after a few thousand miles. Not all aftermarket heads will last 100K miles.