Well if you're gonna spring the strength for a Zakarum Shield then you might as well go for the AP fort as well.
Since neither of your items give +strgth it all depends on if you wanna spend your stat points in strength. I would advise against doing this as:
You can get a dusk shroud with 400+ def and a sacred targe and you only need 86 strength.
If you go the path of higher defense it'd be smarter to put the sanctuary in a vortex shield as you can get higher defense for about the same strength. Then since you already have higher strength you might as well go for a high defence AP Fort.
If you are a smiter you should get +strength from gloves (Dracs), helm (Guillames) so realistically the most you should put into strength is around 110 wheras if you go for the lower strength gear youll only need around 50 strength.
So its all personal choice on higher def but less health (because you have more pts in strgth than vitality) or more health and a little less defense.
The ideal base armours for Fort are: Dusk Shroud (77 str), Wyrmhide (84 str), Scarab Husk (95 str) and Archon Plate (103 str). The next higher defense armour is Hellforge Plate, which at 196 str, is a little too much.
Work out how much strength you will have after your gear, and then make/get one accordingly. If you know that you're going to have more than 103 strength in the end, then Archon all the way.
As for Sanctuary, it's the same deal. Zakarum Shield needs 142 strength, which may be too high. Sacred Targe (86 str) has the highest base blocking chance at 60%, 80% with Sanctuary, meaning you'll save a lot on dexterity to get to max block. Sacred Rondache (109 str) is the next best choice, it'll have slightly higher defense (negligable) at the cost of higher strength requirements and dexterity for max block.
I think Sacred Targe is the way to go for any paladin shield runewords, aside from Exile.
You should definately use Guillaume's. That thing is just too great to pass up. Not to mention it makes your pally look sexc.
There are plenty of items that can grant you the strength you need to use items. Dracul's gives up to 15, Thundergod's gives you 20, and there's always a rare ring/amulet with +str to consider.
You can always a high +str ring or 2 in your stash and use those to equip (bug on) your items, then remove them and let things like Dracul's and Guill's support themselves. Just don't die, or you'll need the rings to pick up your whole body again.
Strength is not entirely wasted on a Zealot or Smiter, or any melee character for that matter. It does provide that little damage increase. A small difference in stats wont make or break your build, if it's only for PvM.
My Zealot has 110 str base, yet has ~210 after items. I still manage a 2.4k life with my 1BO CTA, while low, is more than enough to make uber trist a cakewalk.