Plunger Model 7 Seat Brackets

Hi looking for a bit of advice. I'm a building a '52 plunger model 7 500cc twin. It's almost complete but need to source a single seat. I'm trying to understand what bracket supports front part of seat to frame lug under tank. I was thinking of making one but just wondered what they look like and if they are available to buy. 

Cheers in advance.

Paul