The Rover K Series engine manual.
Dave Andrews' pages.
A Haynes manual for a K-series Rover, e.g. Rover 25 - assuming your car is S2 then you'll want the 99- manual not the -99 manual. I've no idea how much detail will be in here but it may help to demystify some of the gobble-de-gook in the Rover manual
The K is different from many engines, so not sure that a generic book on engine rebuilding will help all that much.
I think that the main challenges are:
Block is decked w.r.t. the liners you'll use,
Crank and rods are still in-spec relative to their markings (all the crank and big end bearings are graded on the crank, block and rods so that you select the correct bearings, however if any part has worn to outside of its grade limits then that will be the wrong bearing!), Selecting the correct bearings
Torquing things up properly.
Cheers,
Robin
Cheers,
Robin