+1 on Zzzeke - - AND - do not connect a 3/4" hose to a 1" heat exchanger!!!!
It is not so much that the engine
may or may not run hot due to insufficient water volume flow - It is that the reduced water volume flow will most probably not be sufficient to cool the "rubber" exhaust
hose. And then the rubber exhaust
hose will overheat and "cook/burn" a hole sometime now or later. Then you will have a world of troubles.