Well,...Since no one has responded with a lead to where to purchase a flywheel puller for the lil Merc 7.5,...I will explain how I remove the flywheel.
Granted I will probably get chastised for suggesting such tactics,...But it is how I've been doing it for 50+ years without damaging anything.
I loosen the flywheel nut, backing it off until the top of the nut is flush with the top of the crankshaft's threads.
Then I have a pal armed with a 'Wonder Bar' (fancy term for a crow-bar) locate a place on the top of the engine block that he can use to pry off and put the end of the pry tool under the outer edge of the flywheel (be careful not to put the end of the tool under too far or it will be prying up on the magneto plate - not the flywheel)
Also being careful when choosing the point on the engine block to pry on so you won't be prying on some sort of small aluminum casting, etc that will easily break off when the pry is applied.
Now,...With your pal on the pry tool and ready to apply a firm steady pry designed to lift the flywheel when he sees you swing your hammer,...You put a brass bunyan or other soft metal type item on top of the flywheel nut and give it a stout smack straight down with your hammer.
If your pal is prying at the right time and your smack with the hammer is stout enough,...The flywheel will pop loose.
Then remove the nut and lift off the flywheel - keeping a close eye on the key in the side of the crankshaft's tapered area as it likes to fall out and hide.
Now that you're in the ignition, which I'm betting is due to no spark,...You may find that the points look horrible - all corroded and nasty. If so,...You are most likely looking a 'Maker points' not 'Breaker points'.
I'm not sure just which ignition you will be confronted with without a serial number.
Anyway - IF they are maker points you don't need to polish them - they're fine and the problem is commonly that the white plastic insulator blocks that separate the points' wire out to the switchbox is cracked and the spark is going to ground through the evil lil insulator blocks.
They will be what you'll need to replace.
If you find that you have a common old school magneto under the flywheel you will most likely just need to polish the points and be done - if the coils aren't cracked or swollen, etc.
Thom