White attack (with no sunders or debuffs on target) for 115-150: (6.25*((115+150)/2)) = 828 white damage over 10 seconds.

Threat Generated by White Damage = (828/10) = 82.8 Threat Per Second purely from White Damage.

With no raid buffs (Except Bleesing of Sanctuary) and providing no attacks crit, providing (WoW Gold)I do not get a windfury totem but also assuming all attacks hit and nothing is resisted, at 81 spelldamage, I generate 548.1+25.4+82.8 = 656.3 Threat Per Second.

With raid buffs, reckoning procs, windfury or wrath of air totems, crits, sunders, improved hunters mark, factoring in the increased swing speed when you parry an attack, sunder armor, and any other buffs you may aquire (Leader of the Pack/Moonkin Aura/Imp Spirit) you can easily expect to gain upwards of 700, 800, 900 threat per second. Finally - It does not factor in any increased threat coefficients from Seal of Blood alone - These calculations are based entirely on Seal/Judgement of Blood's damage * 190%, and do not include any additional forms of threat that it may generate.

A Blessing of Sanctuary paladin generating 656.3 threat per second with no other buffs of (WoW Gold)any kind, while only having 81 spelldamage - Hopefully you're starting to realise that generating threat with a low spelldamage build is not only possible, it's pretty easy.

Basic tanking talents, all the usual mumbo jumbo. You've got 3 spare points to spend how you like, and you may take both Stoicism talent points out as they're entirely optional too, allowing you to go 5/5 Ardent Defender (I find it gets leapfrogged in raids, even in it's 2.1.0 35%/30% incarnation.), grabbing precision or whatever else you want really. 

I take 5/5 conviction in the Retri tree since it opens up those extra crits from Seal of Blood and white damage crits are never bad. I don't know is JoBlood uses spell crit of melee crit, but it seems to crit more when I spend points in conviction too. They're optional and can probably be taken over to Holy for Divine Str/Int talents.