Help do i need a new motor

[noelm]

A head gasket is exposed to high pressure and heat, making one would be tricky, but as I said, I am pretty sure you could buy one.

[Billmack]

I have a 1997 Suzuki 115 HP, before accepting “parts are no longer available, hard to get”,  have a look at these guys. I’ve used them before and it’s a seamless process. 

https://www.boats.net/catalog/suzuki/outboard-by-year

[zmk1962]

This is a great educational intro on changing a 2stroke head gasket:

But I’m still skeptical how you are getting 120psi per cyl (good reading) with a blown head gasket. The cyl pressure would leak into the water chambers if the gasket was compromised. The water system runs at very low pressure compared to the cylinders. 
If we believe the pressure test - that to my knowledge indicates a good gasket and no cracks in the head. Happy to be corrected here.

But the water got in from somewhere.  

I would double check the fuel, oil and air intake system for water. Drain all the carbies. 

Also, I would remove the suspect cyl spark plug (and leads from the other plugs) and crank the head a few times to expel whatever is in that cyl. Then spray a bit of WD 40 into that cyl and refit the plug and leads. Prime the carbies and start the motor.  Then check again that each cyl is firing (pull leads) one at a time. 
 

You have nothing to lose. 
cheers Zoran