Hello Chas,
Head removal on your SR engine requires removal of intake and exhaust manifolds and the air shroud which fits over the manifold bolts.
You also need to disconnect the injector pipes and may have to remove the fuelpump sidecover to loosen the lower pipe joint. also ease out the
rocker oilfeed pipes from their rubber fittings and hope they don't crack.(Earlier ones may have brass fittings to unscrew). Injector can then be
pried out of head to protect tip from damage. Do not rotate engine after loosening head, to prevent cylinder lifting and allowing dirt in under
cylinder-to-crankcase shims. Measure and note thickness of gasket and shims,(and order of placement). Check condition of head-to-cylinder surface
for burning or damage,as it may need machining or lapping to seal. In this case you will need to set piston to head bump clearance, which is a process
requiring access to micrometers etc, and some patience. A service manual is handy at this point, or I can try to describe procedure if requested,
Hope this helps, Regards Combustor.