i used the c-clamp and pin method for about the first 5-7 times I did reassembly's and just started using a new method that I find to be quicker and easier for me.
get the receiver and trigger plate installed on the stock and bolted together front and rear, then use an appropriately sized punch thru the trigger plate and into the bottom of the top lever. this will allow you to move the bottom of the top lever however needed to center it up in the trigger plate recess.
I can't say it's the best way, but I like it a bit better personally.