Agreed. Upgrade the T3x. PM if you need inspiration or just search for the semi-custom Tikka thread.You are spending a ton of money on barely any functional improvement over your T3X in 6.5.
Finding a used Derby 28 ga sidelock would be my choice. You could probably find both a 28 and 410 for 5K. The only downside is most of them have 26” barrels.