Your best and safest bet is to re-plumb the tank. Even with the small clearance, you can make the brass tubes about 1 1/2" long with a bend upward behind the motor. You can then spread them to either side once you get them through the firewall. Your fuel lines were having to do this anyways, however the lines were kinking as you stated. The brass tubes will not kink and can route them around the motor as you please. This will take away the worry of lines coming off, and not having to remove the tank to get your lines back on if for some reason they have to be removed.