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Never had that problem Matt and I have done it probably50 times, over the years.

I think I see the cause of the apparent misalignment.. The mid I have has been repainted more than once, and it looks like it has been sanded quite a bit at the lower mating surface where the gearcase meets it. So it and the gearcase are no longer flush, because there is some meat missing from the mid at that lower flange.

What I've learned so far, going 49 OMC:
-not as fun as Yamaha to re-assemble. some bolts are frustrating. stuff came apart ok.
-if you want trim (on a short shaft), it is an added cost.
-the exhaust cover design with the 3 plates and gaskets is not good. Too many flanges and edges that are not smoothy aligned for good flow.
-lowers: wear out in a few areas and like to leak a bit. so expect to replace this or that. short driveshafts are impossible to find. gears seem available but expensive. casings, carriers, and clutch dogs are not too bad to find.
-upgrade the water pump and get a 3 blade impeller? the old cast aluminum pump housings look like crap.
-there are desirable carbs: 75hp carbs with primer instead of choke. newer models have this.
-you have to make sure you have "75hp" parts: cyl head, power pack, carbs, tuner. Block + rods if you want the 1975 "faster parts" version (Does this really matter?)
-even if you have Pro50 trim, the desirable config for racing is: faster trim and a 56ci block.

Matt. I don't race but I do run the piss out of mine. I take long rides and never had issues with mine except for the exhaust plates. I've been running a 56 for 3 years now and have no reasons to go back to a 49. In my opinion, the 56 is a better fit for my go fast needs. The gear case never cause me any trouble in over 8 years. I guess once you play enough with these motor, they become easier to work on. I keep a second motor just in case and now have a spare gear case. They're out there for cheap if you're willing to travel for them.

I've been searching for photos of this for a while and finally got to see it first hand (thanks HoundDog!)

1975 Stinger 75hp block factory exhaust port chamfers, compared with a 1973 block:





1973:

Cool.
Is that the only difference?

On the block itself, I think that is the only difference.
Not sure which years of 75hp had these chamfers.

It would be cool to see comparison of 56er blocks as well.
Obviously in a separate post.
Its cool to see the slight differences in ports.
Ive always been confused with the different castings of these blocks

One of the elders should start another thread: "How to finally choose a 56'r". Lots of bang for lots of bucks?

You don't need a new thread

The best 56'rs came from here.
Wienandt Performance Technology, Inc.
Cost approximately $5000.00 US and up. MOD 56 made 115 hp at the crank.

SST-60 & 56ci Modified Outboard Racing
This is my favorite OPC class Mike has been building these for a long time. We have a great deal of experience and a long list of success. WPT has run more than 250 dyno runs doing testing and evaluation work. We should not call it development because the engine is a spec class. But we know were those specs need to be to make the strongest engines. Just check our record.

Modified Package for Inflatable Racing: We can build a trick mod engine with a better block than you can use in SST 60. This would have the cylinder block ported along with finger ports. Head machined to a specific race compression ratio. Special reeds and intake work. Special pistons, and many other little race details.