Hi Bri
Both motors would be ok, The MFA 800 is the high tourqe version but lower reving, about 5000 without the gearbox, if it is 2 : 1 reduction you are down to 2500 then the lost with the prop in the water, posibly down to 1800 - 2000 revs, might not be enough.
The Smiths motor, is it a heater motor or radiator motor????.
If its the radiator motor it has a large current drain, but high power. If its the heater blower motor, they have a lot lower power requirement and on direct drive to the prop shaft are very sutible for tugs, excelent throttle responce good reversing, enormouse torque, so swinging a 130 prop is simple without breaking the bank for an ESC.
Hope this helps
Mark