if the shop needs to take that much material off, your in better shape buying a new car.. its always a good idea to clean up any mating surface when putting new parts on your car. especially the head gasket.
as for materials I just usually get OEM w/e I find is the cheapest from the different oem vendors I resource around the net and locally.
ill drop the links here in a minute.
Part Stores General Performance Shops
Summit Racing - High Performance Car and Truck Parts l 800-230-3030 Xsboost Turbochargers - Canton, Ohio (OH) | Company Profile O'Reilly Auto Parts CXRacing.com kbox
Junk Yard / Salvage Search
Car-Part.com--Used Auto Parts Market WorldCarLink.com (rain guard) Engines & Transmissions: JASPER
OEM Vendors
Toyota 123 parts MagAuto Redline Automotive Part Detail Toyota Parts, Toyota Venza Parts, TRD Supercharger, Genuine Toyota Parts, Toyota Accessories, Toyota World, Discounts on Toyota Parts Toyota Parts at toyotapartszone.com: Toyota Accessories, Toyota Auto Parts Toyota Parts - Factory Original OEM 1stToyotaParts.com :: Original parts for your Toyota Rock auto
Toyota Specific Profomance
SupraSport Driftmotion HorsepowerFreaks Silacone Tubing supracarparts.com : Toyota Supra Used Parts : MKIII mk3 Supra turbo CT-26 engine transmission intercooler suspension intake AFM wheels lights mouldings, performance mods, japanese, import, racing, Blitz, Greddy, TRD, Apexi, HKS performance parts, information, pictures, photos, mods SupraStore.com Twos R Us - Parts for Toyotas from Club MR2
I just dropped my part store bookmark folder.. lol have fun.