# yum install -y http://rpms.famillecollet.com/enterprise/remi-release-7.rpm
# yum install -y yum-utils
# yum-config-manager --enable remi
# yum install -y php74-php-{opcache,pecl-apcu,pecl-memcached,cli,gd,mbstring,mcrypt,mysqlnd,pdo,xml}
# yum install -y php74-php-fpm

# vi /etc/opt/remi/php74/php-fpm.d/www.conf (以下を変更する)
listen = /var/run/php-fpm/php-fpm.sock
listen.owner = apache
listen.group = apache
listen.mode = 0660

# mkdir /var/run/php-fpm (pid用)

# vi /etc/opt/remi/php74/php.ini
date.timezone = Asia/Tokyo(timezone以下は任意)
memory_limit = 256M
upload_max_filesize = 128M
max_file_uploads = 2000
max_input_vars = 20000

# vi /etc/httpd/conf.d/vhost.conf
ProxyTimeout 300
<VirtualHost *:80>
  ServerName php74.genesis.ne.jp
  DocumentRoot /var/www/html/php74
  <FilesMatch \.php$>
    SetHandler proxy:unix:/var/run/php-fpm/php-fpm.sock|fcgi://localhost
  </FilesMatch>
</VirtualHost>

# systemctl start php74-php-fpm
# systemctl enable php74-php-fpm
# systemctl reload httpd

普通にアクセスすればPHP5が起動、virtual HOSTとして登録したものはPHP7が起動する。
PHP5、PHP7の共存