Looks like you have your work cut out for you
Depending on the age/condition of those exhaust manifolds, they might need replacing. Search "exhaust manifolds" for a lot of threads about them. They only last 5-7 years in salt water use, and maybe 12 years in fresh water use.
I wouldn't trust that makeshift hose from the circulating pump to the thermostat housing for too long. Should be a 1 piece molded hose.
Regarding photos: If you highlight your link then press the IMG button, so the link is between {img} and {/img} , then the photo will show up in your post. (except with square brackets, not squiggle brackets)
Size limit = 1024wide x 768 high
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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings