<VV> Synthetic Oil again

[Chris]

I've poured tens of thousands of dollars into the restoration of my 
convert and expect to get it onto the road this summer (in texas).

Everyone seems to agree that if synthetic oil is to be used, I should 
wait until after "the break in period."  I have two questions.

1) Is the "break in period" defined as 1000 miles, or 3000 miles, or 
some other number, or is there something about the functioning of the 
car that would tell me the engine is fully broken in?

2) Do the recommendations for oil weight viscosity change for a newly 
rebuilt tight engine?  Living in Texas, I would gladly use 20W50 in the 
summer provided that is not too thick for a freshly rebuilt engine which 
has just completed its breakin.