Is it possible to order the long barrel 45-70 on the normal handi rifle?

Sure is if you order an accessory barrel... $103 plus $15 fitting, plus $10 shipping(x2). It doesn't come with sights but does come drilled and tapped for sights and scope rail. You can't order a handi with a BC barrel, though, if that's what you meant.

http://www.hr1871.com/barrelAcc/index.htm

I just ordered a BC, great looking rifle!
http://www.legendaryguns.com/H&R%20Buffalo%20Classic.htm

I know that you can order additional barrels for the Handi Rifle in 45-70. But can you order the Buffalo clasic barrel for your SB2, rifle frame?

A Handi-rifle has an SB2 frame, so the answer is still yes. The barrels in the list marked with an * have certain requirements and can only be fitted to some frames, the 45-70 and BC 45-70 barrels are not marked. Please check your Private messages in the Go> My space at the top of the page.