Booster Seat For Future Car Guy

[speED]

I have a street driven 67 Camaro that my 4 year old son is wanting to drive in. The car has a stock rear seat without any seat belts and a 6 point roll cage. Assuming I can fit the booster seat in the car with the roll cage I need some ideas for a seat belt. Obviously the factory lap belt will not work since it lacks the shoulder harness. Has anyone already been down this road, looking for some helpful tips?
Thanks,
ED

[Classic442]

Upgradethe rear seatbelts to Morris 3 point or fab up anchor points for a modern car seat. Though your son may out grow the seat by 7.

[84TXGN]

I'd really reconsider putting him in the back seat with a roll cage. If you do, I'd find a way to put him in the middle to keep him away from the backstays.