I havent looked right into this so I might be wrong, however:
The Bc327-40 appears to be a high gain variant, 250, the Bd140 has a low gain around 25.
So I'd say the '327 in the original design is saturating properly while switching, whereas the '140 is probably not saturating and operating in its linear region hence the heat.
Capacitance might also be an issue being a larger tranny, this'll slow down switching speed, increasing dissipation.
R2 will need adjusting at the very least, and you might need to replace Q1 as well.