Wema sending unit fuel tank fix

[bigeasy1]

I had posted a while back that the dope that owned my boat previously,used sheet metal screws to hold the sending unit to the tank,and that a tiny amount of fuel was leaking around one screw.
As some of you mentioned,I also thought about redrilling and tapping out the holes to a larger size threaded machine screw,and even using some fuel proof sealant.I figured I'd use my air drill(no sparks)or maybe even my hand operated egg beater hand drill.

I called the tech guy at Wema,and he recommended up grading to a Viton gasket,instead of the cork one that came with the unit,and to get what they call an under ring,,which looks like a round horse shoe with an opening.It has drilled threaded (metric)holes to accept provided screws.
The trick is to get the ring up against the inside of the tank,and getting one screw started,so that it doesn't fall to the bottom of the tank.It then becomes a matter of lining up the remaining holes and getting the remaining screws installed.
Of course I would still have to drill out the holes,but only enough to get the new scews in to the ring.
I'm thinking about the best way of holding the ring while I get the screw in as I'll be alone when I'm doing it.I'm thinking possibly about some very fine wire or other means to work as a lifeline to the ring in case I drop it.

So, Any Ideas??? what do you figure the odds are that there's going to be an "OOPS" moment or a four letter rant session?

Here's a picture of it. the part # is FLSU



http://www.wemausa.com/sensors/adapters.shtml#Underring