spark plug question

[mushman]

I've been using Champion UL77V gapless plugs in my 1986 evinrude 150 for years, I've found that they've been harder to come by ,and when running a cross reference on my motor it says to use Champion QL77JC4 which has a gap.I remember looking at the shop manual and it said to use the UL77V, but I also remember a few years back a local boat mechanic said use the JC4's.
Any suggestions, or opinions?.I guess the gapped plugs might run smoother at idle.