I got this far and I was wondering if there are any techniques to getting off the main pullly nut? I think its a 3/4 socket.

Its impossible for me to hold the flywheel at the same time any Ideas?

 

if the motor is still in the car, you can wedge a breaker bar with 3/4 or 19 socket to the frame, then crank the starter.

 

impact wrench

 

Its on a bench with the tranny off and the front cover loose?

I had to go to work so i left it

another problem i have is a rounded nut on the tourqe converter. I thinking of borrowning a welder and welding a bar onto it to break it free?

 

Your best bet is to hit it with an oxy-acetyl torch and get it hot before hitting it with an impact wrench. Some of them you really have to heat up. I recently tried to remove the main pulley bolt from my 13brew and mapp gas along with a 550 ft/lb impact was insufficient.
I actually didn't have oxy-acetyl so I placed the engine on my driveway and had a buddy stand on it while I used a 24" long breaker bar and all my might to crack the bolt free. I think the multiple efforts of heating it with mapp and hitting it with the impact helped.
I used a spare alternator tensioner bracket to hold the flywheel. Bolt it to the rear plate and then to the flywheel to hold it in position.