Not without fabrication. The first picture is a hardtail Z50A, a style that was offered in the US from '69-'71, and the seats like that only fit hardtails, and mount on with two long bolts that pass through the frame's backbone, which is a tube that runs the length of the bike, more or less.
The second photo is of a Z50R, a style offered in the US from '79-'87. Those seats have one bolt near the front of the seat that passes through thr frame, but where it passes through the frame is channel-section, not tubular. The rear of the seat has two slotted ears that hook onto the upper shock mounts before the shocks are tightened down, so the two ears are much farther apart at the back than the front.
If you want to get the seat up higher on a Z50R for seat-to-peg distance, you could look into a Monkey-style seat, which fits the Z50R-style frame but is higher up and kind of overlaps the rear of the fuel tank. They were offered on versions that sold in other markets besides the US, but there are lots of Chinese clones with these kind of seats. I'll try to find you a link.
The Gorilla version of the Z50 also has a similar type of mount, I believe, and it's up there in height too, but it probably wouldn't fit well with the Z50R tank shape...Gorilla tanks were big toaster-shaped things.
Take a look at that seat. It's a Chinese clone of a Monkey seat, and is "on sale" for about $40 right now at Hooper Imports.
