I’m about to install my 289 performer manifold on my stock 67 c-code and was wondering what length 5/16 bolts I would need. I purchased 5/16 x 2-1/2 bolts and I’ m thinking they are too long. I did a search and some people used 5/16 X 2 bolts. Anyone know the correct length to be used? Also, is it necessary to put RTV sealant around the water ports between the gasket and the cylinder head? Is this the right way to do it? I'm using the ultra black silicon. Will that be ok around the water ports? I’m reading some people do this and others don’t. I’m going to use the felpro blue gaskets. Any input is appreciated. Thanks.