If I'm not mistaken, the kaamas came with two different engine packages. I think the Innovations were assembled to 420 merc specs by Innovation. That's what I have in mine. Does yours have what appears to be Gil exhaust?

I think I have a pic of the ones your talking about. Mine look like stock manifolds with stainless risers/elbows. Doesn't look like anything good. I can go snap a pic if you want to see.

Do they look like this?

Another view

yes

Then I'd say they were the original merc 420's.

Did they use Bowtie blocks? I believe I found a date code on the engine blocks and carbs a few years ago and think they dated later than the boat. They do appear to have all the original hardware attached however.

I'm not sure about the blocks, I imagine they used the best available at the time. I love mine. They were tweaked a little before I bought the boat. They start with a touch, idle great, run strong, and are very reliable. ( I hope I don't regret the last part :) )