1971 lower A-arms install

[Clatterville trolley]

I am going back together with the suspension on my 1971 chassis to get it up to roller stage. Been working on the upper and lower (stock) A-arms replacing them using all new parts.
I have the uppers installed and now working on installing the lowers. I am at the point of tightening up the 'caps' on the pivot shaft. Factory manual recommends torque of 280 ft. lbs. on installing new parts. My torque wrench goes only to 200 - any tips on getting it near enough on correct torque short of buying a new 'very expensive' torque wrench?
I don't think that O'Reilly's rents out a torque wrench that large and I don't know anyone that has one that I could borrow.
Thanks for any ideas and / or suggestions.