We have a completly stock 1600 twin port in the beetle we are doing up that needs a head replaced due to a broken exhaust stud fix that kind went wrong. I have found a pair that seemed ok but when I enquired about if they had been machined for unleaded I got the following reply:
"These are auto linea brand -casing stamped GOI 010 013 7513 these are fairly new used heads -they are not machined-you would have to use de compression shims"
I have no idea what de compression shims are. Could these heads be bolted straight onto our standard motor and work successfully or are they not suitable? Thanks for any help you can give us.

just bolt em on , no shims needed

you don't machine standard heads for a std motor

Thanks for you super quick reply.

As they are "fairly new heads" to quote the seller would they be fine to use as is with unleaded or would they need hardened seats like other pre unleaded cars?

Air cooled VW don't need anything special for unleaded, they are fine as they are.

All stock VW heads are okay for unleaded fuel. VW used hardened valve seats from the factory. If for some reason someone had put soft valve seats in there, then it may cause the seats to wear a bit quicker, but this is not likely. If you discover that the seats wear too quickly then you can always have them replaced later on.

they already have hardened valve seats etc

Great thanks for all the info guys.

VW's have aluminium heads, so hard valve seats are already inserted. 91 octane unleaded is fine in a stock motor, we have used it for 6 years with no problems at all. No decompression required.

It won't hurt to use a valve saver fluid in your fuel, nor will it hurt to use 95 octane unleaded. They just cost more. Valvemaster brand is a common simple product to use. Don't use it in any vehicles with catalytic converters though.

I would still cc the heads to work out what CR it is going to be before just bolting them on