coil springs are diff between bb and sb cars ... also sometimes there will be a frame diff (just a heavier ..or sometimes a conv frame in place of the standard one.)
not all ss chevelles are big blocks either ..
boxed lower arms in 66 .. are really rare they normally were open and have holes drilled for the u shape peice that bolts in w the sway bar .. 442 /cutlass rear bars are the perfered part to add on (there heavier) add this with a 70's Trans am/F body 1 3/8's front swaybar and your A boby will corner on rails .(you'll end up losing oil pressure in corners if you dont have a oil lip inside your oilpan too ..btdt in my gto)
i think its Goodmark and danchuk that sells the repop panels/sheetmetal for the chev's (top quality ones without going for NOS ones ) I sold my last nos 1/4er panel for over a grand last month
68 - 72 A body front disc brakes are a bolt on on the 64-67's ,,, and a MUST in my opinion and can be perchased new for between 550-700 ..
one thing ive also been seeing alot in the Abodies is bent frames from early wrecks or improper jacking (i still work on these cars alot, along w/ owning 3 of them ) look on the sides behind the front suspension and just under the front of the door were it transverses into the open channel ahead of the trans crossmember .