I don't believe that the engine bay was any larger in the L series engined cars [PB210] either as there is plenty of room already. At most, the radiator support pannel may have been different to allow the radiator to sit flush with it instead of being extended rearwards to place the radiator closer to the engine fan.

There is so much room in there that it was possible to fit this Holden V8 & auto trans into this B210 sedan. Yes, it's street legal & was at the Datnats in Goulburn last year.

If this will fit without firewall or tunnel cutting, then so will an L series.