Well, for your BJ-3 you have 3,952,375 listed but on my megamek I see 3,592,375 listed as it's cost.

For your Trebuchet TBT-5N you have 4,373,500 listed but agan my megamek shows 4,293,500

With those clan weapon additions keep in mind replacing weapons with clan weapons mean jury-rigging them on for extra upkeep and you will not exactly find it easy to replace losses. To think of it in modern terms imagine taking an Abrams and replacing it's gun with a Russian gun. Even if they are the same caliber almost nothing will line up right to try and keep the systems together so you are going to be doing things like drilling new holes to keep the gun in the turret and shaving down places on the turret to make it all work.

The Centurion we can go with it being a CN9-D variant you tore the XL engine out of