:~$ grab-site http://oldgamemags.tumblr.com/ --concurrency 3 --wpull-args=--phantomjs --wpull-args=--phantomjs-scroll "0"

which causes:

       [--no-http-keep-alive] [--no-cookies] [--load-cookies FILE]
                 [--save-cookies FILE] [--keep-session-cookies]
                 [--post-data STRING | --post-file FILE]
                 [--content-disposition] [--content-on-error]
                 [--http-compression] [--html-parser {html5lib,libxml2-lxml}]
                 [--link-extractors <css,html,javascript>]
                 [--escaped-fragment] [--strip-session-id]
                 [--secure-protocol PR={SSLv3,TLSv1,TLSv1.1,TLSv1.2,auto}]
                 [--https-only] [--no-check-certificate] [--no-strong-crypto]
                 [--certificate FILE] [--certificate-type TYPE={PEM}]
                 [--private-key FILE] [--private-key-type TYPE={PEM}]
                 [--ca-certificate FILE] [--ca-directory DIR]
                 [--no-use-internal-ca-certs] [--random-file FILE]
                 [--edg-file FILE] [--ftp-user USER] [--ftp-password PASS]
                 [--no-remove-listing] [--no-glob] [--preserve-permissions]
                 [--retr-symlinks [{0,1,no,off,on,yes}]]
                 [--warc-file FILENAME] [--warc-append] [--warc-header STRING]
                 [--warc-max-size NUMBER] [--warc-move DIRECTORY] [--warc-cdx]
                 [--warc-dedup FILE] [--no-warc-compression]
                 [--no-warc-digests] [--no-warc-keep-log]
                 [--warc-tempdir DIRECTORY] [-r] [-l NUMBER] [--delete-after]
                 [-k] [-K] [-p] [--page-requisites-level NUMBER] [--sitemaps]
                 [-A LIST] [-R LIST] [--accept-regex REGEX]
                 [--reject-regex REGEX] [--regex-type TYPE={pcre}] [-D LIST]
                 [--exclude-domains LIST] [--hostnames LIST]
                 [--exclude-hostnames LIST] [--follow-ftp]
                 [--follow-tags LIST] [--ignore-tags LIST]
                 [-H | --span-hosts-allow LIST=<linked-pages,page-requisites>]
                 [-L] [-I LIST] [--trust-server-names] [-X LIST] [-np]
                 [--no-strong-redirects] [--proxy-server]
                 [--proxy-server-address ADDRESS] [--proxy-server-port PORT]
                 [--phantomjs] [--phantomjs-exe PATH]
                 [--phantomjs-max-time PHANTOMJS_MAX_TIME]
                 [--phantomjs-scroll NUM] [--phantomjs-wait SEC]
                 [--no-phantomjs-snapshot] [--no-phantomjs-smart-scroll]
                 [--youtube-dl] [--youtube-dl-exe PATH]
                 [URL [URL ...]]
grab-site: error: argument --phantomjs-scroll: invalid int value: 'http://oldgamemags.tumblr.com/'