Temporarily install the teflon gasket and make a mark aligned with the valve guide.
Place a small dab of JB weld at both ends of the port floor and tilt it into place. Make sure the gasket is correctly located and does not slip out of place when tightening the manifold bolts. Sealer is not needed on the gasket.
30mm ports should be opened approx 1mm wider and higher around each side of the guide at 10:00 and 2:00 near the guide similar to the cobrahead shape shown below . This is important even on street bikes.