BUT, I didn't do the other install, a shop did it

I believe I can fiberglass this configuration though, I am very meticulous and the main pain in the butt is just framing it so everything is straight and symmetrical.
So you don't think I will run into cancellation problems with this type of setup? Oh I see face them completely flat, no angle, hopefully no cancellation.
2 10s would go nicely there though could 2 10s get as loud as 1 12?