The MAC-shaft speed will be 1175/6=196rpm. So if you want 85rpm avarage cadence, you need 196rpm/85rpm= 2.3
overdrive ratio between motor and cranks, for example
42T chainwheel and 18T freewheel, or
30T/13T is possible, if you use the wider 1/2x1/8 inch chain, there are 13T freewheels available that can be threaded on small 30x1mm threaded hubs. Personally I would go for 32T/14T, since both 32T chainwheels and 14T freewheels are commonly available for the 1/2x3/32 (=common 6,7,8-speed) chains. A 14T freewheel with 20mm inner dia hub can be ordered from cyclone for example. I use the same.
As an output sprocket we will find something that fits the 25mph speed you want. That is 321rpm for your 26" outer dia wheel. If you use a durable 13-34T cassette, you will need a 321rpm/196rpm*13T=21.3teeth sprocket. 22T should still make a very good hill climber.
BTW, I have no idea where to get hollowtech cranks in canada
As long as you have 68mm bottom bracket width on your frame, there shouldn't be any problems with mounting your motor, using 2.5mm /0.1" steel sheets.