Keep your current cleveland engine and build that up into a 351 (393 stroker if $$ permit).
How deep is your back pocket
Rough guess to nearest thousand $ you're going to throw at it? What are your desired 1/4 mile times and/or horsepower figures?
Anyway........yes, best to do a full strip down rebuild with that block (if it's in good nick) and hasn't already been over bored/rebuilt at some other time.
Standard practice is to rebore to 30 thou. What you can do is buy a 351 crank, keep your 302 rods and buy some new "short deck" forged or hypereutectic pistons ($$ budget) to fit the longer conrods (new bearings / quality bolts etc).
Heads can be reconditioned and/or fully ported with all the fruit (heavy duty valve train gear........again.....how much $$
). Your 302 heads have the closed combustion chambers which are good. By the time you bought 2nd hand 4V's and rebuilt them, you'd still be up for some serious $$.
HOWEVER......by the time you price up all the head work and new valves/springs etc you'd be pushing $3000+ for a good race combo (heads alone). So my suggestion, if you haven't heared about them yet, is a set of new aluminium heads. $3500 for race ready bolt on jobs that would crap all over the factory iron ones. Fully working iron heads belongs in the 70's and 80's. Surprisingly, there's been a lot of technology and research thrown at the mightly cleveland this last few years.
Have a look at these:
Good electronic ignition.
4:1 pacemaker extractors and at least twin 2.5" system (cam/rpm dependant).