never Pumped Water

Long story short, 2 trips to local repair shop and was told everything fine, took boat out and within 4 mins extreme overheat. Melted exhaust flaps, shift cable. bellows, pump guide. Serial number 534000, believe R or Pre Alpha. Has hook on top cap. After pulling it apart found water passage where tube from pump goes into upper gear box was at least 50% clogged. Need Bellows, shift cable, complete pump assemble and seal where drive shaft enters upper housing. Melted shift cable where could not get it to go into forward gear. Was stuck in reverse. Dropped lower and was able to move shift arm so I can remove upper. Would really like to find exploded diagram so i could get correct parts. Is shift cable the same as a Alpha one gen 2? It looks like a different drive bellows, has 2 clamps on it. Any help would be appreciated. And yes i am worried about condition of engine but without any water flow and stuck in gear i can't test engine.
Thank you,
Guppy

use the newer shift cable that is "aft entry" just need the special tap. Basic transom kit will have evertything else . Search "mercruiser manual 6 in pdf" I`m sure you will find it
If the drive if off after removing the lower unit first shift into neutral and stick a hose in the water inlet

What sort of consumer protection do you have in your area against this sort of incompetence? I should think that this is the shop's problem to fix, not yours. If it were me my first call would be to my lawyer. You will probably have to sue in small claims court and be able to show that the shop's work led directly to the failure. Don't touch the boat until you find out if you are entitled to relief under the law.

Feed water to the engine directly and run it before you do any work....