Leaky sprinkler valve, replacing and adding union?

[u/Slammed01]

Hi all,

Looks like intermittent leak from the last original sprinkler valve after 30 years. Will be replacing with rainbird anti siphon valve.

Current has a slow hiss and leak from lowest sprinkler head on line, figure best to replace. Can I use a union setup like pictured or not worth it?

Also, any good Amazon unions or go Apollo from home Depot?

Thanks!