G'day Ozzie,
I bought one of these earlier this year for a semi scratch build yet to be started. It has genuine J Bass width at nut but configured with a G Style headstock which is perfect for what I have planned and measures 20 cm along the top edge, just enough room for 4 in line or maybe MM 3 + 1.
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https://www.ebay.com.au/itm/202815446784

Cheers, Waz