You have the right idea. The swap will be well thought out. When I add aftermarket items to the 305 I will make sure they fit the 350 soon to come very well. My other toy is a 68 400 Firebird that has a 68 Gran Prix 350 horse block , the correct #16 heads, balanced short block, crane cam that keeps the exhuast valves open longer for better exhuast scavaging . I chose it due to the heads are only rebuilt & not modified other than a 3 angle valve job & correct valve springs for the cam , comp cam 1.52 roller tip rockers, edelbrock performer rpm intake & edelbrock 750 carb, hei distributer with a recurve kit, hooker headers with a flowmaster american thunder exhuast & a msd ignition box . I am also changing the 68 from an automatic to a stick. The rear is a 3:55 posi.