we still have eth free petrol here,,we have a 10% cheap option at most stations,,but are not condemned to it yet,um,,eth has caused fuel system foul ups here on later cars latetly,,ask if they have any asbestos based gaskets(keep a straight face),i dont think you should open up the top end if you dont feel confident about tackling it yourself,having said that plenty of guys have gleaned enough info from here and other sites to do what was needed in similar cases,,have you looked in the FAQ section?,how tooled up are you?good wrench and socket set at least?are you prepared to knock some skin off your knuckles?umm,with all due respect,plan A can become plan B within a few bolts being undone,i think the shop is stooging you,try and find a second free opinion,cheers.