Swapping a 307 olds for a 350 olds is just as simple as swapping a 305 Chevy for a 350 Chevy... The mounts are the same and the wires are the same. Just unbolt the engine that is in there, label the wires you unplug so you plug them back in the right place if you don't have good enough memory to do it without writing it down. Then lift the old engine out and lower the new one in... It's a piece of cake. It's even easier if you delete the CCC Carb and Distributor if your state allows. Really all you need to do is remember where the starter wires go, the ground wire, tachometer, distributor power wire, and alternator wires go. I might be forgetting something... But seriously, guys named Bubba from Alabama that didn't even go to elementary school can pull this swap off,so don't be scared of it. All this swap takes is time and getting your hands dirty.
I'd do it for you in a couple hours if you can wait for warmer weather and bring an engine hoist. :lol: