Ideas on what's causing my click/tick/rattle noise?

actually i can comment on the big end bearings, the big end should be slightly oval
wider at the parting seams. when installed it is pulled into the appropriate round shape and the bearings are crushed at the parting line
if the crush is too much the bearings hang up and seize becasue the sides at the parting line bow inwards
if the crush is too little the bearings ride round and the tang section can drive the bearing to a crooked position and it will hang up and seize on 1 edge or the other
did you get the big ends sized? or did you just use rods with new bolts..new bolts dictate that you need a resize.
was your crank ground in the correct direction and polished. if it is a nodular iron crank the grain is impotant grinding in one direction creates a journal with more friction than grinding in the other direction. factory manaul has details,
thinking about your issue i looked it up last night

as the final polish is done during break in, too much friction and hence hot at this time is not good

Dave