1973 340 detuned?

most engine kits i've seen are for 68 to 71,so i figured if i'm going to freshen up my engine just go for the earlier pistons to boost up the compression. the engine runs good right now the way it is,but like i said earlier it's been parked for atleast 5 years,which i did start it and let it run while parked every 6 months or so.
the distributor is electronic stock,if i remember right the timing was set with the running at i think 3000 rpm to full advance. a friend of mine set everything up,he got into details while doing it,right down to changing airbleeds in the carb. he spent alot of time setting everything up years ago