It will be really hard for you to find 188 heads here or in North America. There were bugger all on cars here, only a few hundred pairs. And in North America they would only ever have been on the lowest performance 350ci engines from about 9/68 through to 8/70. Most likely only ever on 2BBL 8:1 truck engines. They would have all gone in the scrap bin just like 90% of the 173's made for HQ.
290's you'll find a lot more as they are the standard 307 head for 1968 engines built at Tonawanda. They are also the standard head for the 1968 Tonawanda built 250hp 327, possibly also the 210hp 2BBL 327 used in Camaro if the engine was Tonawanda built. But again, they are the lowest performance head for passenger use in that model year so lots will have been scrapped.
Most of the 290's you will find in Australia will be off GMH assembled Pontiac or Chevrolet. Most of those I find are cast in 1967 although there are some of those engines with 1968 date codes, the bulk were 1967 cast. So if you are looking for correct heads for a GTS327 won't be easy as 1968 model year engines started in August 1967, and GM cast probably 60% of the blocks and heads used in a Model Year in that August to January period, then built just what was needed after that, wrapping up in July, and re-tooling for the next model year. GTS327 engines were first assembled 3/4 of the way through March 1968 so heads for those are almost always going to mid March onwards.
Regarding local 290 heads, I've probably bought 10 pairs of them. They are never advertised as 290 heads, if they are people ask stupid $. But often I find them in images and they are only $100 a pair or thereabouts. After all they are common low performance heads that were always removed and replaced with Fuelies. I think all of the ones I've found have been Parisienne or Impala heads other than one pair, maybe two off GTS327.
Edit - also confirmed for you. 1968 290 heads untouched are 19kg without any valve hardware. 1969 188's are 19.2kg in same state.
Edited by user Friday, 8 September 2023 1:44:43 PM(UTC)
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