Korean War B-25

[seadude]

For a future project maybe late next year, I had the thought of building a B-25 Mitchell, but in Korean War service. I wanted to do a Whif as if the A-26 Invader was never used in Korea, but the B-25 was instead.

Is it just simply a matter of painting the B-25 black and using the decals from an A-26 on the B-25, or would I have to make other modifications to the B-25 kit, exterior and/or interior?

* Paint the B-25 black for a nighttime bomber and strafing aircraft.
* Eight .50 cal machine guns in the nose.
* Keep the machine gun pods on either side of the cockpit.
* Keep the upper fuselage gun turret.
* Keep the tail gun for rearward defense.
* Lose the waist guns. Not needed.
* Add underwing HVAR rockets for strafing attack runs.

I have the following two kits that I can use decals and parts from:
1/48 Monogram F4U-5N Corsair (For the underwing rockets)
1/48 Monogram A/B-26C Invader (For the decals)

[Captain Canada]

I'd lose all the defensive guns and add lots of hardpoints 

The yellow band would look awesome on the rear fuselage of a B-25 !

[CANSO]

If you don't have the B-25 kit yet, you might consider starting with a B-25C/D rather than with a J model. The former doesn't have a tail turret, waist guns and the top turret is further back. You can change the top (and eventually the bottom) turret to a remote controlled one (as on the A-26 - you can use them from the model you already have).
You can add more hard points under the wings, as mentioned above, but you can also use some external "Tiny Tim"-rockets under the belly. PBJ's used them in the Pacific in WWII. In real life the USAF borrowed the "Tiny Tim"s from the USMC during the Korean war too.
I myself started a conversion once, which was planned to become a "PB2J-K" for the Marines in Korea, but I never finished it. The main change I did was a new elongated nose (based on the B-25H canon nose) with 4x20mm (or 30mm) guns in the lower portion and a radar in the upper part. Something like the F9F Panther's nose, but not so pointed. The 4x20mm are a better weapon than the 8x0,5 machine guns.The other changes included new engines, like these of AJ-1 or B-26E, not with the many S-stacks as seen on late B-25D and H/J models. North American had this "super strafer", designated NA-98X with very nice and steamlined nacelles with redesigned intakes for the carburetors. BTW the B-25C/D kit comes with the old engine fairings without the S-stacks. 4-blade propellers were also a must...at least for me.  The wings had to be elongated and to receive on their ends external fixed tanks (like on the AJ-1 or FJ-1). Since you are building a strafer and not a bomber, the bomb bay will be used probably for an auxiliary or a drop tank, but even so the external tanks look good and more modern.
Cheers!