Refinish older grips

I have a set of walnut grips that I would like to refinish. Any tips would be great.

I used this for years on fine gunstocks.

https://generalfinishes.com/wood-finishes-retail/oil-based-wood-stains-sealers/oil-based-seal-cell-clear

Follow with a few coats of this

https://generalfinishes.com/wood-finishes-retail/oil-based-topcoats/arm-r-seal-oil-based-topcoat

Most good woodworkers stores should have it.

Follow the instructions.

What is on them now?  I generally want to use the surface treatment that's on them now, if I am not removing all of the old surface treatment first.  

I've always liked Boiled Linseed on walnut.