If that 427 was put in back in 1967-68 then converting to a BB heater core and cover would indicate an impressive attention to detail. Today, the first thing cloners do is put in the BB heater box but in those days nobody cared.
The following three early BB dealer conversion Camaros were performed on 350 cars and the SB heater boxes were left in place.
Here's a pic of the first Dana Camaro, converted from an SS 350. Note the SB heater hose routing and the SB shroud.
Here's the first Nickey conversion, overseen by Dick Harrell, and it too has its SS 350 SB fan shroud.
Third is this Nickey/Bill Thomas conversion, possibly the first BT conversion, and it has a SB heater box. Note that it has what looks like a factory BB fan shroud. Hmmm.
Granted, these early dealer conversions were done before the SS 396 was avaialable so they had to stay with SB heater cores and shrouds but even when the 396 Camaro was in production I'd be suprised if street racers converted their SB heater boxes to BB units when the Rat went in. Can't wait to hear more about this car.