Up right and plug holes/pipes with rags and keep indoors if possible and cover with a tarp, I would be tempted to spay "spay" grease over it if your are storing for a long time, you can jet this off when brining it back to life.
Agreed with Drifty on this. I would be tempted also to keep the flywheel and clutch kit on it as well if you know its a good clutch. Also if you are replacing the truck with another one the same then keeping the ancillaries attached as well would be advisable. You never know if your new vehicle is going to have a good alternator etc. A light dusting of WD40 is good enough to stop the block from drying out and going manky.
Modifications: Its a Frontera that is heavily disguised as a Mk.1 LWB Isuzu Bighorn 2.8TD Lotus Edition. Hi-roof modification. EGR valves and birds nest of vacuum pipes removed. Front Manual Locking Hubs. Rear Limited Slip Differential. Yota Surf steels, with custom paintjob. (cheers Gregster) 33x12.5" R15 General Grabber AT 2's. +2" suspension lift. +3" body lift. Cat 1 Thatcham approved alarm. Irmscher wheel arch flares. Full body restoration/respray. (cheers Gregster again!)