TSSC club shop says £315 (member price) that will almost certainly be your head reconditioned done by Ivor Searle who have a good reputation. £600 is just way too much, there will of course be carriage. Canleys will not be a rubbish recon. That price would include a skim, clean new guides (or bronze inserts) new valves, springs and the seats sorted, all in all about £300 is a fair price plus carriage of course their price will include labour to pack your cylinder head and send it to their reconditioners, but also consider any warranty, if you supply the reconditioned parts the garage have no responsibility for warranty of those parts so if there where to be a failure you would have to pay labour to refit, this is why I do the work myself