i've never had to spend more than $800 to build a 305, and that is counting new pistons, new cam & lifter, rebuild kit, ( reuse the old crank ), bored the cylinders, valve job, cam bearings installed, new pistons pressed on old rods ( rods checked )

Here is a trick I was taught by an old timer to remove plugs:

heat the plug with the braizing tip of a torch
throw water on it
immediately turn it out. Usually it will go the first time

For the cylinder ridges: you can buy a ridge cutting tool, I've used them and they do a good job if you follow the directions. It is very important to cut the ridge before you pull the piston, or you could damage the ring lands on the piston. However, if there are ridges, then you probably have to bore the cylinders anyway, so the old pistons are trash, so just drive them out using the wood handle of a hammer. ( good info for next time )

A 305 is a pretty good motor to learn on. Good luck