I installed a Maradyne Mm-a1090002 cab-heater in my Hisun. It was a fairly simple install with the most difficult part being to find the proper location for the heater body. It has to be located so that the heater hose, etc is not blocked by OEM air filters, body frame, etc. On my 750 Sector I determined that by centering the heater body a few inches directly below the gauge cluster worked perfectly. The 5/8" heater hose comes out just to the right of the air filter tube.
Since the firewall is plastic, I placed a large piece of stainless steel on the outside of the firewall for a backing plate. I drilled a couple of 1" holes in the plastic firewall for my 5/8" heater hose and spliced them into the upper and lower radiator hoses. I spliced the upper heater hose into the upper radiator hose and the lower heater hose into the lower radiator hose. No shutoffs, since I figured I could easily install them later if I need them. I bought 8 ft of 5/8 heater hose and 8 - 1" hose clamps at the auto parts store. Then I bought 2 pex tubing tees 1" X 3/4" X 1" at the hardware store to splice into the upper/lower 1" radiator hoses.
The electrical is easy by running the black ground wire and red hot wire to the power supply (cigarette lighter) in the center dashboard. By removing the power supply you won't have to drill large holes in the dash and you have the correct wiring needed to wire the heater switch. I installed another power supply below the front of the bench seat in the middle. I did that because it's easy for the driver to access and it was near the battery box for an easy installation.
After I refilled the radiator overflow with anti-freeze, I pulled the Hisun's front wheels up on my trailer with the back wheels on the ground. I did that so the radiator and overflow bottle were higher than the rest of the cooling system and any trapped air bubbles in the heater core would head for the overflow. If that doesn't work, let it idle with the upper radiator hose clamped shut (needle nose vise grips) directing all the coolant towards the heater core to speed things up. Remove the vise grips when the radiator fan turns on and then put them back on when it shuts off two or three times.
I have about $175 invested for parts and heater for the project, and my heat laser reads 190 degrees when the heater is on.