Big Dave (knower of all things), if I am understanding you correctly, putting headers on my 69 will require the motor mounts to be replaced (with the one most parts stores are going to give you anyway) but the alternator doesn't need a bracket because the mounting was changed in 69. Ultimately, I change the motor mounts and I am good to go with the headers?
What size collection pipe do folks recommend? My son's firebird (89) has 3". I know opinions on brand of header are all over the place, but is there a reasonably priced set that folks seem to like? We used hooker shorties, but being a bit older, long tubes fit these babies.