Port match
A port match will help it but it's hard to say how much. Manufacturing tolerances play a part in how well things match up. I've seen some that were very close and others that were quite a way off. I'd guess anywhere between 5-15 hp is what you'd attain but that's just a guess. Sounds like allot of work even if it's 15 hp. If it was apart it would be a no brainer and I'd do it. Since it's put together I probably wouldn't worry about it but that's just me.