The book seat back is inclined at 5.7 inches over a height of 21 inches. This seems a bit upright when compared to some sports or race cars many of which have more like 9 to 12 inches worth of inclination over a similar distance.

What do you think about this? Has anyone tried greater than book angles? Does anyone know what other seven type cars actually use?

most people use real seats and not just put upholstery in the car like the book did.

In this case, you can put spacers under the seat mounting bolts to give the angle you need. Or use adjustable seats

OR get a comfortable angle on your normal road car seats and measure that.

OR make up a simple wooden jig, lean against it at variable angles and take yer choice from that.

atb

Steve