stripped sending unit screws in plastic tank

[JHouk]

Getting ready to launch my 88 V20 for the summer. I've been working on it for 2 years & is now sea worthy. Took it on a trial run in the river, boat ran awesome but it had a slight fuel smell. Turned out to be the sending unit gasket. It turns out all the screws are stripped. Its a plastic tank. I'm going to try the next size screw to see if I can get them to grab. Any ideas?
Thanks in advance.