RE: Welcome to Club SAITO !
No need to touch the cam housing, put the piston at TDC to relax valve springs, remove rocker cover, remove four bolts that hold the cylinder down. They will be unbelievably tight, pull cylinder upward about .25 inch, do the work and re-assemble. I like to cut an Allen wrench down to remove the cylinder bolts. Again do not remove the cam housing as I did here.
PS, there is no base gasket and not need to replace the rocker cover gaskets.