Looks like the importer's name, KBI Harrisburg PA was engraved with one of those dremel attachments that you use to carve your initials on a fishing reel. The word "Sporter" appears to be added to the receiver as an afterthought. Styrofoam a little dinged, Safety flicked a couple times (can see mark on receiver), but otherwise untouched. All accessories intact. Can't see if angled or straight without pulling stock off.  I know very little about AK's, so TIA.....

You can check to see if angle cut from the top by taking the dust cover off.

I've never seen a angle cut MAK90. The shitty thumbhole stock makes it look like it's weird because it goes over the rear of the receiver. I shitcanned the thumbhole stock on my Mak90 years ago. I personally think the Norinco's are some of the best built. My Norinco Mak90 is of much better build quality than my Maadi.

Check the Chinese Rifles page of my web pages.
mywebpages.comcast.net/jfreeman246/index.htm
KBI imported 2 types of MAK-90 rifles the Norinco and Poly Tech. A pic of a KBI imported Poly Tech MAK-90 Sporter is on my web pages. A new in box one will go for $400- $500 depending on where you are. As up north prices tend to be on the higher side than here in the south.