Let's be practical. You will do just fine going with the standard-issue .490, as a starting point. During your progression you may choose to go to the .495. I know I did and now pretty much settled on the .490. You will find that availability will not be a problem as well as pricing. I just sold my .495 double cavity mould as I had enough run to last me awhile. ...
Keep it simple and;
Be Safe !!!