Straight Blades on 60" MMM ??

[Flintknapper]

I'd think the straight blades will not work as well as the OEM design. I found out you need 'high lift' blades if you use a bagger on a rider, the regular 'lift' versions clogged the 'tubing' between deck and bags.
The OEM blades were probably designed for THAT style deck,to help lift,cut, remove the clippings.

I think by 'Straight Blade' the OP mean't they do not have an "Off-Set" to them.

The OEM blades on my Land Pride Finish Mower have a similar 'Off-Set' of about 3/4". Probably there to help protect the bolt.

I also use a flat mulching blade and just lower the deck a bit to compensate for cutting height.