When overhauling the cylinder-head/s assembly, replacing as many of the wear & damage prone components as possible with new parts will simplify the reassembly and subsequent adjustments required to set up the valve-timing and valve clearances correctly.
Pay particular attention to the valves, valve-guides, cam-chain tensioners/guides, the camshaft lobes and bearing journals.
Performance could be returned to factory-fresh levels with a smooth, quiet and powerful power delivery with the correct course of action taken.
Other related items you may wish to consider:
Try this pro-workshop gasket sealant: 08C70K0234M. Easy to apply with superb results.
Add as many items as you wish to the same shopping cart, new tensioner 1283224A01 valve retention collets 1293227A00 and stem seals 0928905008 for example, and still only pay the same single fixed price shipping cost.
This component may have other applications in the Suzuki model range.