I think you really need to sort out that fuel leak. It's possible you'll pull air in there too, and that's won't be good I'm sure.
I've run the wrong plugs in mine for years whilst racing, and it always seemed fine. Got loads of stick at the NSR meet, mostly from people whose bikes didn't run...
You should let the bike warm up before riding it, as the various bits of metal in the engine all expand at slightly different rates, and the bore will wear premature;y if you hammer it from cold.
If the jetting is close, the bike shouldn't foul at idle, but remeber that the mains aren't doing anything at tickover - it's the pilot jets and mixture screw that is providing the fuel. If the mid and top end feel good, then the main jets are probably close. Now you need to work on the part throttle settings.
You didn't think it'd be easy did you?
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