10mm to get rocker cover off
then i'd think 13's for the head bolts

then its just hacking the wiring and pipes to the inlet and getting the exhaust end off

they pull off in minutes, ive done headgasklets start to finish on em in 20 mins

sure you dont want to take a mate and take the whole engine? loads of space to work, unbolt the box/top mount and you just drag it out standing on the strut tops. downpipe, inlet the lot