I had some issues with my tri-power reinstall last year also. Back in '92, I had used Permatex 98H and I tried that first last year. My recollection is that (a) there's a yellow teflon tape for gasoline/etc that I used where the fitting blocks went into the carbs but that (b) sealants (tape or goo) at the flared fittings is not desireable as it's the flare that must achieve the seal, not the treaded part of the fitting that presses the flare to its seat. A tricky part is tightening enough to get a seal and also getting the angle so the fuel line lines up. And, yes, some connections have gaskets/etc; e.g., the big fitting to my cengter carb. Anyway, it's great when you finally succeed.
It worked for me as my problems were at the threaded blcok-to-carb points. I do believe someone objected to the teflon, but not sure.
BTW, I've established a habit of opening the hood after each drive, to help things cool but also to check for any leak that might be developing.