I setup a samba share called 'company' with a create mask of 770. When I create a file in that share, the permissions on the file are 760 instead of 770. Should they be 770 because I specified the create mask?

[company]
path=/home/company
browseable = yes
writeable = yes
guest ok = no
directory mask = 2770
create mask = 770

$ ll /home/
total 8
drwxrwx--- 3 testuser testgroup 4096 Feb 19 10:21 company

$ ll /home/company/
total 52
-rwxrw---- 1 testuser testgroup 8714 Feb 19 10:21 New Microsoft Office Excel Worksheet (4).xlsx

Try:
force create mask = 770

Testparm doesn't like force create mask:
Unknown parameter encountered: "force create mask"
Ignoring unknown parameter "force create mask"

force create mode seems like it should be doing what I want judging by the man page for smb.conf, but i'm still getting the same behaviour.

I set /home/company to 777, and in smb.conf, I tried setting force create mode to 777 and I get the following permissions on the newly created file:
-rwxrw-rw- 1 testuser testgroup 8714 Feb 20 10:27 New Microsoft Office Excel Worksheet (8).xlsx

Setting create mask in smb.conf to 777 results in the same behavior.

Sitting down and thinking about it now, samba - or more to the point SMB doesn't really know anything about executable bits on permissions - that's why it's not being set.
Consider it a 'feature' rather than a bug. To show an example, try copying an executable windows file that runs on its own - maybe VNCviewer or putty. Now try and run that file as a member of the group rather than the owner. Windows should run it just fine.