So, I'm in your situation now. My mechanic had had excellent luck with SBT new, installing 6 engines from them in the last 2 years (3 mr-1s) and all are still running.
I was still not convinced due to horror stories online, and looked for a used one with low hours. Found one from a freshwater state with 90 hours. He says the engine is very clean and leak down was perfect. I should get my boat back in a week or two.
The MR-1 engines are generally well known for being reliable and solid, but the salt water use prior to my ownership and/or other corrosion from not flushing longer/better caught up to me. I flush on the last day of the weekend with salt away for a few minutes, unsure how much of the issue was me alone vs the prior 8 years. If i could have done anything different, pulling the exhaust manifold preventively would have saved me, but it requires pulling the engine due to the design. I don't know yet if I will be pulling my engines in 5 years to check and replace/refinish if needed, but I'll think about it
I think SBT seems to be improving, which is one option. Lots of shops use them, check with your local mechanic what he would do and what their local experience is. I hear they have a set up where their new engines are actually fired on for testing before shipping. At least that should catch any early duds. The best known shop in Houston (not my mechanic, he was too full to take my work WFO) also uses SBT blindly and says they are just fine. Nobody I spoke to was willing to rebuild locally because it was not economical to do so and they have had good experience with SBT. WFO does performance work too and it's well known in town. If SBT released how many engines they sell and how many are returned for warranty work I would be more persuaded.
The other option as 1.8l is longer life and there are more salvaged, is to update both to 1.8 from used craft. More expensive, but when you look at the price of a new boat, it stops seeming uneconomical.
Don't worry about it now too much, your options might improve if your are keeping your body for many more years and you end up needing one. For now, if it was me (it was) the best freshwater used engine will get you out of a jam. And if I had pulled the engine at year 12 or 13 to check the exhaust manifold I would have saved both. As it is new head on one and used engine on the other. Exhaust rusted all over. wish me luck.
