The Leupold Vari-X III 2.5 x 8 in silver finish is the very scope I have on my Whelen. It is a nice fit, properly scaled to the rifle, IMO. They are being discontinued by Leupold so you might pick up one at a discounted price right now.
If I had to quibble just a bit, the gun's balance is slightly skewed to the butt, which is of course a function of the 1-A light taper barrel and the .35 cal bore. It's not really objectionable, just a different feel than other #1's, but that is what gives it a unique personality.
I had a little trouble with misfires with mine, which I discovered was due to a slight bit of shoulder setback on factory Rem brass (one or two out of a given lot). Since, of course, the Whelen headspaces on the shoulder, you have to watch for this oddity. I have taken to sorting brass and checking head to datum line length with a Hornady gauge. Intend to only neck resize brass that passes muster. Seems as thought RL-15 is the powder of choice in the Whelen.
The Whelen is truly a phenomenal chambering, one could hunt almost worldwide with it and not want for much more, short of going after the Big 5.