85 Weekender. port motor replacement

[ehood]

A couple questions.
I am replacing the port motor mercruiser 260hp 5.7 350.
There seems to be a motor with a single part main seal and one with a two part seal .

Does some know which this model has?
Can you have one motor 260hp. & one @ 300hp ? Since replacing the port I thought I'd update the one.

 

[SCORPIO]

The pre 1987 engines had two piece rear main seals. Post 87 engines are one piece. You can use the later version but may need to change flywheel/coupler. I have a bad port engine on my 89 300 DA and am probably going to install a 300+HP engine this spring and replace the starboard engine next year when the budget permits. I have talked to several engine people and this doesn't seem to be a problem. That said, I will have to manually sync the engines due to mismatched power curves. Also, I won't be able to run WOT as the higher HP engine has a higher max rpm. I don't do hole shots so not worried about unequal thrust or yaw. I'm going to put closed loop cooling on my new engine too while I'm at it.

 

[ehood]

Thanks for the info.