Old Glass,
One trick is to find a sporterized No 4 foreend - the wood on either side of the receiver is high enough to cover the cut-off slot (and you can inlet for one, if you wish). These can be had for under $15 US on ebay or the like, makes for a decent practice piece.

For Express Sights, check out
MSR219 MK10 MSR 1 Fixed 2 Folding Leaf Express Sight (round bottom)
MSR221 MK10 MSR 3 Folding Leaf Express Sight (round bottom)
http://www.sarcoinc.com/mauser.html

These are $35-40 each, IIRC - there's a deal if you buy three at once. The bottom contours are apparently for Mauser barrels, so you'll need someone to relief cut it for your Enfield's.