Yes. That is how my Blade was configured. I ran the retrieval line down through the grommet in the tramp for the mast rotator, instead of to the back beam. Kept me facing forward when uni and dousing.

The Viper has the back-to-back blocks running up the mast. It goes like this: Dyneema ties off to the forestay sheave (?), down the mast, through the back-to-back block, up to the block for the spin halyard and to the head of the spin. A separate line runs from the the spin tack, into the pole, exits the main beam end of the pole on a block inside the spin pole, up the mast, through the back-to-back block, down the mast, through the mast mounted halyard cleat, through a small block on the main beam, back through a ring on the tramp and back forward through a hole on the tramp and into the spin snuffer.

The spin lines for the Viper came stripped in all the right places, so I am going to stick with that system for a while. It requires some thinking when rigging, but seems to work fine one set up.

I apologize for the layman's terms, but it is all I know (there is probably some fancy word for back-to-back block).