#1 If you need to keep the crank from rotating with the engine fully installed, try placing the gearbox in the highest gear & stand on the brake pedal while your mate torques it up. No mate? Then pull the handbrake on firmly & give it a try.

#2 As a starting point, fill the clutch master cylinder resevoir, refit cap, then slowly pump the pedal up & down for a dozen strokes or so. Check the fluid level. If it is down, then top it up & keep going. If not, then get your wife to push the pedal while you expell the air at the end of each down stroke.
I was actually able to bleed my 810 clutch cylinder single handedly this way. It took a week or two of driving before the last bubbles worked their way up.
Two man bleeding is best, but if you are on your own, then give it a try.

#3 I used engine oil because I was too damn lazy to get lighter stuff & the engine ran well anyway. There was always a little engine oil left over when I serviced it so it was used in the carbs as required.
I suppose I was just being an 'individual'

The book says
Gasoline engine oil & carburetor damper oil.
Specification..... API SE [Further details. refer to recomended SAE Viscosity chart.]

Well what do you know, just check the chart in your owners manual for the recomended engine oil in the temperatures that you will be in, & make a chioce from the various overlaping grades.
Hell, I was right anyway. Who'd a thought it.