Good choice on the Marlin X rifle, have two of them in other cartridges and they shoot well. As to a scope. Check www.natchezss.com
for a Weaver 40/44 3.8-12x44 A.O. scope. Its about a $200 scope that Natchez is selling for $120 or $130 depending on reticle. This is an aspherical lens design scope (heritage is 35mm lens camera design), made in Philippines and has excellent optics. Owned one for a few years now and quite happy with it.