If you are going to upgrade the valves and port your heads to increase performance,
get some 1.94x 1.50 valves. These heads work well when fully home ported.
here is an example of a 305 build up using the those heads. it makes 343HP.
This lil motor with the Lunati 224deg Hyd cam likes to rev.
Yours will too, if you build it similar and want performance.
Pick a converter stall and gears accordingly : this motor wants a 3000++ stall and gears 4.10+ to run.
Advertized stall will get you about 500 less stall behind a 305- 307 .
a 10" "3500 stall gets you about a 3000 real stall..
If you are going to install on a stock 307 short block use a thin felrpo 1094 head gasket to max the compression ratio, for the cam choice. ya it matters. 10:1 is where you want to be for a motor like this (92 octane).