Ok cool - thanks!Since you revived it and decided on a insert, and you liked the BK before, check out there website they have a couple new inserts that are really nice looking.
As to your other questions....
Custom surrounds can be made by a machine/metal shop.
There is no reason not to use a block off plate. Chimney breathing is silly....
![[Hearth.com] **Best Insert for (ICF) Large Ranch - what would you buy!? [Hearth.com] **Best Insert for (ICF) Large Ranch - what would you buy!?](https://www.hearth.com/talk/data/attachments/183/183979-6123978889a448efec3eafac2106ec71.jpg?hash=URmqoVqGhP)