MGP vs F grade timber

The plans I have for my workshop specify F7 pine for the all the framing, which I'm having a bit of trouble finding. I asked the building surveyor and he said I could substitute MGP12, which is also not so easy to come by, MGP10 seems to be the most readily available. I've done a lot of looking around on the internet and most of what I've found places F8 in between MPG10 and 12, with no mention of F7. One document I found from the HIA has a table that places F7 just below MGP10 on the...

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