Question about finding replacement transistor

[Yamin]

I've got a generic power supply (output 12V, 20A) with a blown transistor. The transistor turned out to be a chinese made one P13009 The package is TO-3PB. I think it could be a MJE13009 knock off. But the package is different.
I was wondering if I could replace them with a 2SC4140 since I have them in my parts bin.
The ratings are similar from what I can see and some ratings are slightly higher than the faulty one.
P13009:
VCEO = 400V
IC = 12A
2SC4140:
VCEO = 400V
IC = 18A.
These are the two main ratings I looked for, what more should I look for (in the future as well when I have to find equivalent replacements) and could I replace it? Also what is the significance of matching the package style apart from lead spacings?
Thanks in advance.

[abdulbadii]

As long as the replacement is greater, to mean better, than or equal to all the ratings of the replaced one it'd be fine
inc. T_c T_a must be equal or higher than the ori.

[rob77]

it's ok, but i would definitely replace both transistors on the primary side with the same type.