Pergola Posts

I'm in South Australia and I'm trying to find 140x140 (at least MGP10) permapine pergola posts as per my drawn plans but I can't seem to find anybody stocking posts that large.

I talked to one sawmill here who said that if they do them there's a good chance of having heartwood in posts that size so they might be prone to splitting and warping.

Anybody know where I can get posts of that size or should I just laminate some extra bits onto standard 120x120 posts.

Maybe hardwood is the way to go but some of the Merbau posts at a local supplier I've looked had split.

Any suggestions welcome or suppliers details.

Thanks, Travis.

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