Re: any difference between carbs on 68 1000ss and 72 1400
You'll lose a lot of power, 'cause the 100hp carb throats are significantly smaller than 1400 carbs.
The stud patterns are completely different as well, 100hp carbs' studs are straight-across from each other, whereas the 1400 carbs' studs are at a diagonal (staggered). Not to mention linkage issues, chokes, etc.
If by some means you were able to make 100hp carbs work on a 1400, it'd probably run terribly lean and have detonation problems, unless you installed larger main jets. And there'd be no way to know what the proper size is, you'd have to experiment.
I'd recommend sticking with any set of carbs from a 99-c.i. motor, rather than trying to make those 90-c.i. motor's carbs work.
Any set of carbs from a 99-c.i. motor, rejetted with .084 main jet on the upper carb & .082 jets on the middle and lower carb, would be far better than a set from a completely different design powerhead.
Here's a set of 115hp carbs at auction on eBay:
1979 Mercury 115 HP Outboard Inline 6 Carburetors Carb Used | eBay
Another possibility would be a parts motor on your local Craigslist. There's usually something on there for a reasonable price.
IMHO, HTH...........ed
