Just putting it out there for the one getting into this...
You need more than a BFH and a socket to properly disassemble cylinder heads.
You ought to have a some kind of spring compressor ideally and at least a file to knock down the valves keeper/lock grooves..or else when you take them out...they will destroy any guides that were still in spec or usable. Stock valves are not very hard or strong, they break and they also distort at the lock grooves. The locks hammer the groove edges outward.
Someone once told me he thought if he turned the valves as he forced them out that it would give a knurling effect...
No... more like a swirly slide for the oil to super hwy to the bowl is all that does.