it is easy compressing the springs and getting the valves out
the hardest part is putting the collets back and knowing that the stem seals are properly put in
i nearly topped myself after refurbing a redtop head, took me 6 hours to do 4 valves as it took 20 - 30 mins to get the collets in, it must be something that you find easier with experience
then i found out that i cracked the shitty ceramic valve guides that would be brass if the head was the later type, in the end i paid a specialist in bromsgrove a ton to refurb it for me and i sold it on for 250 on ebay 🙂, i bought the engine for a ton also 🙂
machine mart are decent, i bought some big heavy duty ones for about 20 quid