David has a very good reputation & I believe he'll be able to make the shorter arrows for you if that is what you wish.
If he can't, or if you just wish to check prices, Jerry @ South Shore Archery is another very top shelf man to deal with.
I agree with Cossack, 2" groups @ 20 yds is not real good, and 4" is crazy at a range where it should be possible to shoot one hole groups, at least under 1".
DO you know how to figure your Forward of Center, or weight forward to get best accuracy? If not I'm sure both those gentlemen at the shops named above, or folks here can help you with that. Really if you don't know this, you can just tell the guys at those shops what broad head & it's weight you're using & they should be able to make up a set of arrows that can well improve the accuracy you are getting at the moment.