Slant Six age and size?

On the peanut head being heavier
The original peanut heads definitely were, vs the drool tube ones. The latest of them in the 80s though I believe they shaved some weight from.
I was at another FABO members garage last summer with the head that is on my engine, and he had a few /6 heads on a work bench, some good and some junk (experimental, ruined by excessive porting) he invited me down to run mine on a flow bench, just for comparison sake. My '77 head was the heaviest of the bunch. He had a drool tube head, and a couple of newer peanut heads, as I remember one was from an 80s pickup truck engine. That 80s head was a peanut plug one as mine is but was much lighter than the one that I brought down.
I lifted mine onto the flow bench, and while he was setting it up suggested that I check out the heads on the bench that was against an adjoining wall. As I flipped them over to look at the features he wanted me to see, I noticed right away how much difference there was in heft.
In my case I don't care about how much heavier my head that's now on my engine is, as mine is going into a pickup truck in which case a few pounds here and there won't mean much like it would in a car that gets raced.
I'm also going from a cast crank to a forged crank motor, and the oil pump I bought for it is cast iron where the one on my truck is aluminum. If I were looking to shave every 1/10 of a second off of a track time, I'd worry about it more