Just for general info, correct me if wrong. A 307 chevy has the larger diameter journal stroke of a 327, but the smaller bore of a 283, This block can be bored .120" to 4" then be a new 327 ready to build, with the larger, cooler running crank journals!
Find some 2x camelhump heads w/ 2 1/16" intake valves and you will be set!

The 307 can't be bored .125".

use a 350 block since it has the same bore of the 327 at 4 inches, bolt in the 307`s crank, use 327 pistons and you have a 327.

When I was grinding crankshafts for a living, we did bore some 283 and 307 chevy engines .120. Made the 283 a 302, to be built to 67-9 Rally Camero special engines. the 307, became 327, when people were unhappy with the 350.

A 350 that does not need boring, is probably still on the road. Of course, since you are buying pistons, yes, the 350 could be bored .030, for .030 o.s. 327, with the 307 crank.