I'm sure they are okay but if they only have one bolt per port you will have exhaust leaks at the port....I have two sets of thru bolt 460 logs right now for sale one set on ebay and the other hasnt had anything done to them other than the snails have been pulled off and will give you a new set of gaskets.
http://www.ebay.com/itm/460-Harman-Marine-Thru-Bolt-Jet-Boat-Exhaust-Logs-and-Snails-/150743216212?pt=Boat_Parts_Accessories_Gear&vxp=mtr&hash=item2318fef054#ht_500wt_1202