if you decide to shorten get a really good smith to do it, and ask around about his rep. as there are some smiths that are dodgy and others that are craftsmen, choose wisely who you use. go for reputation not cost basis as the crown is very important to accuracy.
shorter barrels tend to be stiffer and a little more accurate, however there are many long barrels that are very very accurate. the best is a balance 18 - 22 inch is a good range.
some of the best shooting teams in the world shoot with long barrels but I suppose they are shooting off the deck.
I can recommend an outstandin