Nostradamus worked on cars? I thought he predicted the future? HA HA! I am only good at remembering the past , and learning from it. I have been playing with Firebirds for almost 50 years. When I got out of the ARMY in 1975 I bought my neighbor's 1968 Firebird hardtop, OHC-6, automatic. It was my daily driver for 16 years. I learned a lot on that car, had 6 different engines, and converted to manual transmissions. At the end it had a 400 4-speed. It literally rusted out from under me, that was my favorite car ever. So that cylinder came alive? Excellent! As for the manifolds, just clean up the gasket mating surfaces, chase the threads in all the holes, put a little schmear of RTV around the water crossover holes, and use a torque wrench, and always use anti-seize on anything exhaust related. Over the years I have learned to upgrade exhaust bolt to stainless steel, with anti-seize on the threads, you will be glad you did down the line. A note about rings- to have new rings be worth the trouble you need the cylinders to be bored and honed. There is a ridge at the top where the rings did not touch and it needs to be removed, cylinder walls checked for taper and roundness, pistons cleaned and checked for skirt wear. That usually means oversize new pistons fitted by a shop to get the specs correct. Trying to hone a cylinder with a honing tool on a drill is not the way to go. That is something racers do between runs on cylinders that are almost perfect to begin with. Plenty of people do it and say it worked out great. Our rule-of-thumb is that if hand-honing was good enough to get proper ring seal, the cylinders were so good they didn't need touching to begin with. I know we all like to do something once and be done. But with hot rodding in general, and especially old cars like these, sometimes you need to try something out, and if it doesn't work, take it all apart and try something different. It's just part of the 'fun' of old cars. .