could a dog still be shown if it is 2 inches bigger than the breed standard, and is bigger all round. He is very good in every other way.

It depends on the breed. Some have height restrictions to which dogs must conform, and they are measured, and others have 'ideal' heights, where anything too far removed from this will be penalised to a certain extent. If the dog is otherwise superb, he will probably get away with it as often as not.

It will also depend on the competition and the judge. Some judges will consider a bit of extra height more of an issue than others.Some judges may think there are worse faults. It has got to depend on breed aswell...a couple of inches over to a yorkie is a lot more noticeable than to a large breed.
As with all faults..if the competition have less noticeable or severe faults then you won't do so well.If the competition is of a lesser standard then you'll do ok...in other words its all relative!
At the end of the day you can only give it a try and see
Archer

SBT standard says 14-16 inches is standard size but dogs have been known to be 18 incehs and go on to be Ch's such as Megabyte Black Bomber. Other breeds are more standardised than SBT's and any SBt owenr will tell you size and type vary greatly so dependant on the breed your dog is guess two inches may or may not notice.

Depends on the breed entirely!! In mine the recommended max height for a stallion is 27 inches but I have a champion stallion hound who is 32 !!!