Saving Old Seagulls

Hello all from the wilds of western Canada (North Vancouver)
Having a Mutineer 15 sailboat and wanting to go places (and return) I naturally aquired 4 Seagulls in the last ..uhh..month
Lovely things, I am much smitten by the simplicity of design, reliabilty etc
I've done as much research as seems possible and Identified all my Seagulls and the years (or close approximates) when they were manufactured
I have:
1959 40 plus - villiers carb, metal flywheel top with silver flywheel, chrome exhaust and drive tube, brass tiller! with longer thumb throttle control
1972 40 plus - villers carb (part blk plastic), black plastic flywheel top with gold painted flywheel (needs new throttle cable) (was siezed now runs)
1978-79 40 plus - Bing Carb (needs square cover) otherwise the same as above, metal tank
1966 40 minus - same as the 1972 40 plus except for the smaller bottom end (Came with spare prop, 5 springs, washers ,cotter pins, tiller extension and adorable manual , parts book and warranty)

All run, start very easily, circulate water when they should, and seem to have no cracks in the blocks

So I was going to enquire as to a few things:

-I was trying the 40 minus vs 40 plus
The 40 minus sits with the water just at the bottom of the larger exhauast tube (is that too shallow?) I find some conflicting info on this on the web(some say 1-2 inches above the exhaust outlet, some say 1- 2 inches above the pinch bolt, some say 1-2 inches up the exhaust tube) Which is it? (I only tried it out to the dock)
The 40 plus sits with the water about 2 inches up the exhaust tube, it seems to start okay and run fine, Is that the correct depth or too deep? ( I used it on a couple of 45 min runs back to shore)
only have the one boat and limited space(apartment) so I'll probably sell whichever is inappropriate
I'll keep at least a couple though...I'm not heartless

- the 78-79 40 plus seems to leak some fuel from one side of the crankcase(right where the top half joins the bottom)
I'm using a roughly 20/1 mix as it has the bing carb , will using more oil help this problem or do I likely need a new gasket?
It's not tonnes of fuel just noticeable and continuous. I checked the bolts to ensure none were loose
And otherwise it seems to run fine and I have about 1.5 hrs on it
-I'm looking for an original square carb cover for the same engine, I fashioned a serviceable one out of aluminum but it'd be nice to have real one, The one it came with was, I believe, formerly a bean tin

- the 1959 40 plus seems to bog down when more throttle is applied...is this a clogged carb jet? or something more sinister and costly ?

When I got my 1972 40 plus it was siezed but with a bit of patient work and point cleaning it started on one go!...amazing engines!
I had to make a new choke lever for it..it had a nasty one fashioned from a tin...or beer can..!

Thanks

Is it true that Seagull's props spin backwards down there?

And speaking of props (this will sound dim) but after removing the cotter pin, washer and spring...how does one get the $%@%$# prop off ??, there's a wide thread but I'm disinclined to force it after that

Funny!
That's what my girlfiend says too!
I'll have a carefull look-see at the my seagulls as well
Thanks

The standard recommendation for outboards is to have the cavitation plate level with the bottom of the boat, for free water flow to the prop. The water pump housing should be underwater while the motor is running as well. If those things can be done with the water no more than 3-4" up the exhaust tube, all should be good. Clean the carb on the 1959 motor, much better motor than the later ones.[opinion]

Thanks Phil
I appreciate the information
One can only learn so much from research, actual experience is better
I cleaned out the carb the other day and it seems to run well now...of the three 40 minuses I have it's the only one that doesn't leak fuel out of the crankcase, I noticed it doesn't have the stops for turning like the newer models so you could theoretically reverse it if you wanted....though I don't think I'd need to
I'm beginning to share you're opinion that it's the best one though, Generally made with less plastic parts and strangely in the best running shape overall
I hope to give it a test run out in the inlet tomorrow
Thanks again
And thanks to My Aussie mentor
(Inspector Collector), I had another look at my prop shafts, cleaned up some dings with a file and happily switched a couple props around