I put a Leupold VX-II on my 1917 Enfield years ago. Love that scope to this day. Unfortunately it cost more than the rifle. I opted for the 50mm lens so it was quite a bit more. The standard 40 mm VX-II are reasonable if I remember correctly.
http://www.cabelas.com/product/Hunti...3Bcat104535180
Shows a 40 mm 3-9x zoom for $300. A little over your budget but compare it side by side with another option if you can. That's how I picked mine. Cabelas giant gun counter had dozens to try, plus the store is so big you can actually play with the zoom a bit.