I am interestedin your ACOG, but I'd like to see a pic of the "crack"...not so familar with them, and hadn't heard that they all crack.... As for your questions: Chromelining....I couldn't find anything that said it was, so I guess not. It does have a front sight. And A2 F/S. LPK? I dunno who made it, I bought it from CMMG. As for more specific pricing:
Just upper 525 shipped
Upper with Buffer 550 shipped
Upper minus buffer...plus bayonet (525 upper+45 bayonet=570 shipped)
I hope this helps!