Mercury "ez Shift" Lower Units. Help!

Hey

I have a 1980 Merc Tower of Power 90HP and recently found out I need to replace my lower unit due to my prop shaft being bent. I ordered one off ebay that was supposed to be compatible but it turns out the unit that I ordered is an "EZ Shift" model and has a spring loaded pin on the top of the drive shaft. The original lower unit I dropped from my motor did not have this "EZ Shift". I spoke to a couple marine mechanics and both seemed somewhat unfamiliar with this situation and one told me I can just grind the pin off and another told me it will fit anyhow and may just change my gear ratio requiring a different prop.

I am uneasy about simply shaving the pin off because if that destroys the lower unit I can no longer resell it to buy a different one and I'm out the money spend on it. I'm not certain on if the spring loaded pins function is with the upper end which would make me think it's actual ok to grind it off or with the lower end which if shaved off might result in the gears unable to engage. The "EZ Shift" lower unit clearly wont fit as you can see the pin hitting and it just wont go.

Is anyone familiar with these "EZ Shift" lower units? Is it really ok if I just grind the pin off or do I need to sell this lower unit and buy one without the "EZ Shift" feature. Any help would be greatly appreciated.