vi golf: command on a motion?

hello people,

Does anyone know how to get this done even faster:

ma
}
:'a,ms/foo/bar

even if it's short, I really would like to have
something which work the way I abuse the ! command in vim:

!}

actually write a range on command line like

:.,.6!

so I just have to replace the ! by s/foo/bar and i get the job done.

anything i missed in the doc to be that concise with vi?

regards.
marc