There are tons of articles on the web on 305'*.
This is a good article on 305:
305 Chevy Engine Blocks - Engine Masters Magazine
HOT ROD'* 400hp 305
Even though I also agree that a 350 is a better starting point, if you already bought the 305 there are options.
My first question is how much are you willing to spend on the 305 build?
Some of the first folks really to have discussions with are engine builders. You are going to need boring,deck,porting etc.
My last 305 build was flat top pistons,30 over, Crane cam, roller rockers, ported,headers,edelbrock intake & carb 4 barrel,fluid harmonic balancer, Accel hei coil, and the distributor was re-curved on a sun pro distributor machine,w/variable vacuum advance, thst really woke it up.
Never had it on dino, but lets put it this way, no problem getting tires lit.