The book time to do both head gaskets is 7hours 18 mins (it's not worth just doing one in my opinion), anyone who knows what they're doing should be able to do it in less time than that if they don't encounter problems. If you've got an early 10.5:1 cr engine it's worth fitting composite gaskets to knock the cr down to about 9.9:1.
Problem is that whatever you're told about someone's knowledge and competancy with the Rover and the V8 you won't know until they do the job just how good they are.
Prices given before the job can only ever be an estimate and this can obviously change but an initial figure shouldn't be more than 8 hours, with a view to getting it done in a day if it's only gaskets.
Make sure you're certain of the diagnosis before you start pulling the heads off.
