to do it by the book you should replace your gaskets, but....i have reused gaskets alot and never had a problem. (Intake gaskets that is, and clutch gasket) I also use some silicone on my intakes to make sure i got a good seal, you don't want any unwanted air goin through there.
My opinion on yamabond is don't use it. I hate it, there is a couple different kinds but it just seems to sticky trying to put it on. I would recommend hondabond HT. It works really well, but i have also used silicone on a lot of shit. If you get the two surfaces clean silicone will hold really well. But if your just getting your cylinders ported you should just replace your base and head gasket and silicone your intakes and be good to go.