A 2-band Enfield with brass furniture does sound like a Pattern 1858. The markings on this particular gun appear to be somewhat mixed - perhaps the rear sight was a replacement. The L.A.C. marking would indicate the London Armoury Co. Ltd. A rear sight graduated to 900 yards should be for a P53 - I believe all the Short Rifles had sights graduated to 1000 yards or more (or at least the P58 and later models).
The rest of the markings indicate that this Enfield was probably made by a Birmingham maker, under British Government contract. The VR (for Victoria Regina - Queen Victoria) beneath the Crown generally (but not always) indicated a Government contract, and the Crown/B/69 was an inspector's mark for a Government gun from Birmingham. The WD (War Dept) mark is, of course, a definitive Government mark. The TOWER marking was just a standard military marking for commerically made Enfields of the period, and did not mean the Tower Armouries or a London association.
P58s of the normal configuration are not rare - in the States, it is more common to see those made for sale to North or South, rather than an earlier British contract weapon (like this one). Value depends a whole lot on condition, and where the gun is sold.
Hope this helps,